Focus mode

1. Add option to toggle focus mode to room settings

For this introduce new room property focusModeEnabled.

2. Hide navigation elements for participants if focus mode is enabled

Stop using routing service for room detection, use room service instead which provides a stream of the current room.

Prevent from showing news indicator for content nav bar item when displaying nav bar again after disabling focus mode.

Also fix animation for hiding mat-drawer (nav bar).

3. Synchronize presentation with participants if focus mode is enabled

Introduce new FocusModeService for creator/presentation which sends FocusEvents to backend.

When navigating between contents, comments or starting the live feedback, a new state is published.

With participants FocusModeService components can subscribe to focus event state changes and navigate to next content for example.

The service also handles navigating between features according to incoming events.

4. Show focus mode info notification when entering presentation mode

For this add new type INFO for snackbar which has same duration as presentation snackbar visibility.

5. Modify participants room overview if focus mode is enabled

Add an focus mode info text and a indeterminate progress bar below room info.

6. Add notification for participants when focus mode has been disabled

7. Use feature flag service for focus mode components/services

Closes #1106 (closed), #1114 (closed)