Use correct localizations in user role assignment

Introduces a `LocalizationManager`, which works with tagged services, and uses the correct localizations in the assignment of user roles.

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | none
| BC Breaks     | none
| Doc           | https://github.com/sulu-cmf/docs/commit/328c0eb2ba6415c82f2cf891d7c416528f156275