Before this commit, all mail templates were shared, which was cluttering the UI
for everyone.
Now, each user can have their own templates that they can edit and save. Access
is done through the mail composer wizard, where users can only access their own
templates and templates that don't belong to anyone.
Some groups are considered as admins and can access all templates in
Settings/Technical/Email/Email Templates:
- Sales Admin
- Project Admins
- Helpdesk Admins
- Accountants
- Event Admins
- Recruitment Admins
Task-2504439
Part-of: odoo/odoo#126049