[Untested] Frontend user roles

Roles per user:

* [x] enable multiple
* [x] can always be team member
* [x] cant be scrum masters && product owner

Roles per project:

* [x] Cant have multiple product owners
* [x] Cant have multiple scrum masters

Test
* [] Test

Backend doesnt respond when sending requests:
{roles: ['Developer'], user: 1, project: 1}