This update improves security and control in project collaboration by restricting what portal users (collaborators) can do with subtasks and tags. Portal users can now only link or unlink existing tags to tasks, but cannot create, modify, or delete tags themselves. They also cannot modify restricted fields on subtasks. This prevents accidental or unauthorized changes while maintaining necessary collaboration features.

Restrict collaborator portals to:
 - Change unallowed fields on subtasks
 - Create/Update/Delete tags. They can only link, unlink tags to tasks.

task-3698146

Forward-Port-Of: odoo/odoo#152963
Forward-Port-Of: odoo/odoo#152686