Harmonise Room Notification Settings with Android/Web

[langleyd]

This issue is to track improvements to room level notification settings that bring more consistency across platforms.

The entry point for changing room level notification settings will move up one level from room settings to room info:

Rather than just a toggle to 'Mute Notifications' users can now choose from:

Note on a change in behaviour: In the old behaviour where we just had an on/off mute toggle, the off/muted state actually set the state to "Keywords and Mentions". Under these new options None does actually map to the None state( in line with the other clients.)

As keyword notifications are not supported on encrypted rooms for iOS when changing notifications they only options for available will be:

with an accompanying message:

When room notifications settings are changed via the slide interaction on a room list:

The room settings view will be presented modally and include a user avatar for context:

The following message/link will be added on the room notifications settings screen once we have made the improvements to the account level settings: