Renames RoomDNDView to DNDRoomTile which now provides a separate DNDRoomTile component rather than
clobberring RoomTile, so we can use a draggable one where we want a draggable one and a non-draggable
one where we don't want it to be draggable. RoomTile main is still polluted with DND stuff, but is
now optional.
Remove BottomLeftMenuTile because it was no longer used in the bottom left menu. Just include
the equivalent markup directly in the one place we now use it (in MemberTile in react-sdk).
