Re-enable RoomInfoNotableUpdateReason

[Hywan]

We have introduced RoomInfoNotableUpdateReason to get finer grained updates from a RoomInfo, and to reduce the number of updates for RoomList. Turns out, we had to disable it (see #3728) because a lot of business rules were not clearly defined: the room list was missing updates from RoomInfo. We need to restore RoomInfoNotableUpdateReason, but first we need to define the business rules exactly.

• feat(base): New RoomInfoNotableUpdateReasons::READ_RECEIPT #3680 to make READ_RECEIPT an explicit update,
• notable room updates: have a change to the unread-marker event cause a notable update #3705 to make UNREAD_MARKER an explicit update,
• and so on.

But a lot more are missing, like a new room name, a new room avatar, stuff like that. We need to list them precisely.

cc @manuroe