Before this commit, when the portal user can access to project sharing
views, he can just read. If we just add ir.rule to allow the edition,
the portal could create/edit. We have to allow the project manager to
define the access rights of portal users when he want to share them a
project with the project sharing feature.
This commit adds 3 access modes portal users in project sharing views.
1. **Readonly**: the portal can only see the tasks in the different views.
2. **Comment**: the portal can use the chatter in task form view.
3. **Edit**: the portal user can create and edit tasks.
task-2379518
closes#73341
Co-Authored-by: Yannick Tivisse (yti) <yti@odoo.com>
