The appointment scheduling calendar view has been improved to group appointments by the partners (attendees) rather than just the organizer. This change makes it easier to see when multiple staff members or partners have conflicting events at the same time. The system now displays all partner attendance in the calendar view, helping managers better manage resource availability and avoid scheduling conflicts.

Currently the gantt view for user appointments (dentist, interview,...) is grouped by organizer of the event.

While this works for the purpose of managing appointments it also hides the fact that the partners linked to each user may be attending some other event at the same time.

To make this more clear we enable grouping by partner_ids and we make the gantt view default to that grouping.

task-3452277

WhatsApp message templates that include date and time information will now display in the user's local timezone instead of UTC. This ensures customers receive messages with dates and times that match their location. For event registrations, the system uses the event's timezone to provide the most relevant information.

Before this commit:

By default, all the datetime fields are stored according to `UTC`. If the user
tries to send a template whose template variable is set to a field type of
`datetime` then no logic is written in `_find_value_from_field_path` to
update the field's value according to the user's timezone. It will be sent
according to `UTC`.

After this commit:

In the `_find_value_from_field_path` function, if `field_value` will be received
of `datetime` type then a new function `_whatsapp_get_timezone` is used, which
is added to the base that will return the desired timezone. By default,
`_whatsapp_get_timezone` will return the user's timezone. The
`_find_value_from_field_path` will update the `field_value` according to the
timezone returned and if no timezone is returned then it will take `UTC` by
default. This function can be overridden by any model. e.g.
`event.registration` will override `_whatsapp_get_timezone` and return the
event's time zone.

Task - 3636178

Forward-Port-Of: odoo/enterprise#52208

This update improves the speed of account reconciliation processing in Odoo, particularly for large batches of transactions. The system now uses a more efficient method to match reconciled accounts, eliminating unnecessary repeated calculations that were slowing down the process. Users will experience noticeably faster reconciliation operations, especially when handling significant volumes of financial data.

Instead of trying to find the reconciled lines recursively, we can use the `matching_number`, since it now has a distinct value for each subgraph of reconciliation even for partials graphs.

The situation in 16 was computing the graph by doing one query per level of depth. In 17, before this commit, only one query was done but computing the graph from each node, leading in a worse time complexity. The result was that for small batches, it was slightly faster in 17 than 16 but considerably slower for bigger batches.
This commit just makes things go zoom in all cases.