Meta: Improve UI navigation code abstraction

Attack plan:
- [ ] Move navigation code from `MasterTabBarController` to `TabBarCoordinator`, see #3597
- [ ] Create a Coordinator for every root view controller of the tab bar, see #3597
- [ ] Create a Coordinator for RoomViewController, see #3597
- [ ] Move deep link management from `LegacyAppDelegate` to `AppCoordinator` and create a parser for deep link. Handle first #3595 then #3600
- [ ] Move session management code from `LegacyAppDelegate` to a dedicated class, see #3618
- [ ] Migrate `AuthenticationViewController` to Coordinator, see #3597
- [ ] Manage authentication flow management from `MasterTabBarController` to `AppCoordinator`, see #3618
- [ ] For tab bar, use navigation controller at the right place and put one inside each tab, see #3086

Note: When moving navigation code or creating a Coordinator extract Storyboards from the main one, see #3596