In big databases, the number of tags becomes rapidly huge. This makes
it very hard to find revelant tags. In practice, the same few tags are
usually used in a given project.
This commit:
- Limits the search of tags to the project's tags of the task as well
as to the tasks' tags of the task's project.
- Prevents creating case sensitive variants of existing tags.
- Reuse existing tags from other projects and other projects' tasks
when the user `creates` (or at least thinks creating as the
_name_search would not return the searched tag) a new tag in his project.
task-2735833
closesodoo/odoo#82925
Related: odoo/enterprise#23814
Signed-off-by: Laurent Stukkens (ltu) <ltu@odoo.com>