[ADD] website portal module to display portal in website + user groups: ...

...display website menu based on user groups

- Task: https://www.odoo.com/web#id=8568&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.C1Ps0gZXGqJwbhh8
In the spec there is something about related document access rights. I don't see it anywhere ?