The legacy v2/invoices and credit_card_charges endpoints for new payments are
deprecated by Xendit. This migrates checkout and card sessions to the
/sessions Payment Sessions API redirect flow and charges v3 tokens through
/v3/payment_requests, while still accepting pre-existing v2 tokens (there is
no documented migration path for them) through the legacy
credit_card_charges endpoint.

Session creation:
- endpoint: v2/invoices -> sessions; response invoice_url -> payment_link_url
- external_id -> reference_id, with session_type PAY or SAVE (for
  validation operations) and mode PAYMENT_LINK
- validation operations use the company's own currency instead of the
  generic fallback's arbitrary pick, as Xendit's payment channels are
  activated per country and an unrelated currency can be rejected
- customer.given_names -> customer.individual_detail.given_names and
  surname, split via payment_utils.split_partner_name and sanitized to
  alphanumeric (API constraint)
- customer reference_id is made unique per session creation attempt
  (customer{partner_id}{random suffix}) as Xendit rejects reused
  references and never reuses existing customers
- success_redirect_url/failure_redirect_url ->
  success_return_url/cancel_return_url
- payment_methods -> allowed_payment_channels
- addresses removed (not supported by the sessions API)
- country derived from partner.country_id.code, with company fallback
- mobile_number sanitized to E.164 (+digits only, no spaces)
- card payments with tokenization set allow_save_payment_method=FORCED
  and card_on_file_type=CUSTOMER_UNSCHEDULED
- removed the inline card form and its direct flow (payment_form.js), the
  Xendit SDK and the /payment/xendit/payment route: all methods now
  redirect to the Xendit-hosted payment link; the passthrough
  _get_redirect_form_view override is dropped as well, and so are the
  processing values only the inline form used (rounded_amount, currency,
  access_token)
- the now-unneeded xendit_public_key credential is no longer required nor
  shown in the provider form; the field itself is kept, as dropping a field
  is not allowed in stable
- the session id is saved as soon as the session is created, rather than
  waiting for the webhook, so it is available even if the customer returns
  first

Tokenized payments:
- charge v3 tokens (prefixed 'pt-') through /v3/payment_requests
  (api-version 2024-11-11) instead of /credit_card_charges, using
  payment_token_id; channel_code is omitted as it is rejected when paying
  with a token
- tokens saved before the migration to the v3 Payment Tokens API aren't
  prefixed 'pt-' and aren't accepted by /v3/payment_requests; since there is
  no documented way to migrate them, they are still charged through
  /credit_card_charges with is_recurring set, same as before this migration
- card_on_file_type is CUSTOMER_UNSCHEDULED for a customer actively paying
  with a saved card, or MERCHANT_UNSCHEDULED for an unattended charge
  (operation 'offline', e.g. a subscription renewal), to reduce the odds
  of a 3DS challenge without forcing skip_three_ds: that flag requires a
  dashboard feature most merchants haven't activated, and isn't needed
  for card-on-file charges since the card network's own MIT exemption
  rules already cover them
- channel_properties requires success_return_url/failure_return_url even
  for these off-session charges; built without an access token as the
  charge may run outside of a request context (e.g. from a cron)
- if a v3 token charge unexpectedly still requires 3DS authentication
  (status REQUIRES_ACTION), a customer-present charge exposes the
  authentication URL Xendit returns as the pending_authentication_url
  processing value, and the frontend navigates the top window to it
  directly rather than submitting a form, since Xendit's page requires the
  query string carrying the API key, only accepts GET and refuses to render
  inside a frame;
  an unattended charge has no cardholder to redirect, so it is set to
  error instead of being left pending indefinitely
- create the payment token from payment_token_id; the masked card number
  is not included in payment/payment request notifications, but is
  included in `payment_token.activation` webhook notifications, which are
  handled directly to avoid the extra request; otherwise, it is fetched
  with a GET on /v3/payment_tokens/{id} (_xendit_make_request now
  supports the GET method)

Status sync on return:
- a customer returning from checkout, or from a 3DS challenge for a v3
  token charge, is checked directly against Xendit (via a new
  _xendit_sync_from_provider) before falling back to the previous
  pending-by-default behavior, in case the webhook is delayed or dropped
- the token charge's success return URL now carries the reference and an
  access token when issued from a live request, so a customer returning
  from a 3DS challenge can also be checked this way; a charge with no
  request context (e.g. a cron renewal) is unaffected, as there is no
  cardholder to redirect in that case
- the return controller now also matches `pending` transactions, since a
  v3 token charge is already in that state by the time of the 3DS return

Webhook handling:
- unwrap the {event, data} envelope sent for session events
- look up transactions by exact reference_id match (or external_id for
  legacy credit_card_charges notifications), falling back to stripping the
  random suffix Xendit appends to payment request references
- store payment_session_id or payment_request_id as provider reference
- extend the status mapping: pending (PENDING, ACTIVE, REQUIRES_ACTION),
  done (SUCCEEDED, PAID, CAPTURED, COMPLETED),
  cancel (CANCELLED, EXPIRED, CANCELED)

Upgrade compatibility:
- the inline_form template is emptied rather than removed: the provider
  record is noupdate, so existing databases keep inline_form_view_id
  pointing to it, and removing the view would abort the module update
  (ondelete='restrict')
- _should_build_inline_form is overridden to never build the inline form:
  until the module is updated, the view keeps its old card inputs in
  database, which would otherwise still be displayed and whose values would
  be silently discarded, as the payment goes through the redirect flow
- bump the module version so partners upgrading notice the change

Webhook migration notice:
- Xendit replaced the single "Invoices paid" webhook field with separate v3
  event groups (Payment tokens v3 / Payment requests v3). Databases that had
  Xendit configured before this change stop receiving payment and card token
  status updates until the Xendit Dashboard is updated with the new fields
- remind admins of this by hooking into the daily autovacuum cron instead of
  a dedicated one or an upgrade-triggered migration script: SaaS/.sh don't
  force module upgrades, so a migration script would only catch the
  providers, companies, and admins that existed at the exact moment of the
  upgrade, and a dedicated ir.cron record wouldn't exist on already-installed
  databases until then either. @api.autovacuum methods are discovered
  directly from the Python class, so they run immediately everywhere, keep
  covering providers and admins added later, and can be removed later by
  deleting the method, with no leftover cron record to clean up through a
  migration
- track whether admins were already notified by checking for an existing
  pending activity instead of adding a stored field on payment.provider: a
  new column wouldn't exist either on databases where the module isn't
  upgraded, and the ORM would error on any domain filtering on it. This
  means marking the reminder done re-schedules it on the next run, since
  there's no way to tell "resolved" apart from "dismissed" without a field;
  that's accepted, as the underlying condition (the webhook still needs
  reconfiguring) hasn't actually changed either way
- notify base.group_system, account.group_account_manager, and
  sales_team.group_sale_manager rather than only Sales admins: those are the
  groups actually granted write access to payment.provider and its Xendit
  credential fields, or otherwise likely to own the provider's
  configuration, and covering all three means databases using Xendit
  without the Sales app installed (e.g. through Invoicing or Point of Sale)
  still have someone to notify. A user in more than one of these groups is
  only notified once
- the activity note links the "webhook configuration" and "Xendit Dashboard"
  mentions inline to the Odoo documentation and to the Xendit Dashboard's
  webhook settings, respectively, calling out the October 1, 2026 date after
  which the old webhook field stops being honored. The cron itself stops
  scheduling new activities after October 7, 2026, since there's nothing
  left to prevent once Xendit has already cut over

Task-6373405

Forward-Port-Of: odoo/odoo#277626