Adds Ecuador electronic delivery guide support for stock operations, including XML generation, authorization workflow, reporting, email templates, and related validation. This helps businesses comply with local delivery documentation requirements and manage delivery guide errors or cancellations directly in Odoo.

I refactored `_l10n_ec_send_xml_to_authorize`. This is just an idea to illustrate https://github.com/odoo/enterprise/pull/68468#discussion_r1852085123.