Improve the layout and function of the room context menu

The room context menu is a jumbled mess of actions, so the first idea of this commit is to organize them. The first item is "Mark as Read" because let's be honest, you're going to be using that the most. Then the next "group" of actions are what users can "do" with the room. This is like "Notification settings", "Favorite" and etc. Then there's room settings, and leave.

Secondly, the "Favorite" action now uses the same icon we use elsewhere.

Third, "Notification State" is a weird name for this action and renamed to simply "Notifications".

Finally, the "Mark as Read" action is now disabled when there's nothing else to read.

Before	After