Handle remaining cases for room updates in new room list

For https://github.com/vector-im/riot-web/issues/13635

This adds support for:
* Tag changes
* DM changes
* Marking our own rooms as read
* Our own membership changes

The remaining branch we didn't need was the alternate 'new room' branch, so it was removed.

This is not optimized - optimization is deferred.

src/stores/room-list/models.ts

@@ -38,6 +38,7 @@ export type TagID = string | DefaultTagID;
 
 export enum RoomUpdateCause {
     Timeline = "TIMELINE",
-    RoomRead = "ROOM_READ", // TODO: Use this.
+    PossibleTagChange = "POSSIBLE_TAG_CHANGE",
+    ReadReceipt = "READ_RECEIPT",
     NewRoom = "NEW_ROOM",
 }