Add convenience possibility for switching meals between 2 teams

[Clemens85]

• [x] Enhance "..." in Team-Details for entry with switching meal which opens new dialog
• [x] Dialog: Show list with all other teams that have another meal (refer to autocomplete in participant swap number dialog) and that are not cancelled
• [x] Backend: New rest endpoint which accepts both team-ids
• [x] Backend: Use already existing swap team members functionality (and don't enforce team partner wish in here) and also keep hosting team member the same
• [x] Reload Team-list after success with success notification
• [x] Improve wording in client for indicating that just members are swapped
• [x] Missing i18n
• [x] Backend: Add activity for meals swapped
• [x] Add news entry