[WIP][FEATURE] Feature/editabledropdown

__Tasks:__
- [x] implemented ContactTitle entity
- [x] implemented Position entity
- [x] implemented controller for position dropdown
- [x] implemented controller for title dropdown
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

@christianbader what happens when $position is null?