Always add state.room_id after the configurable ORDER BY. Otherwise,
for any sort, certain pages can contain results from
other pages. (Especially when sorting by creator, since there may
be many rooms by the same creator)

Signed-off-by: Daniël Sonck <daniel@sonck.nl>

Fix test by checking against a sorted room_id array. If there are multiple
rooms with equal order_by values, individual rooms that share this same
value are ordered by room_id. "version", "creator", "encryption"
"federatable", "join_rules", "guest_access", "history_visibility" all
have multiple rooms with the same value, thus need this specifically
ordered id list.

When the direction is changed of the sort to descending, also apply this
to the tie-breaker based on room_id. This makes the whole list flip as
would be expected.

Signed-off-by: Daniel Sonck <daniel@sonck.nl>

Line can be on 1 line due to sorted_by_room_id_desc being shorter than
the array.

Signed-off-by: Daniel Sonck <daniel@sonck.nl>

"joined_members", "joined_local_members", "version" and "state_events"
are ordered in descending direction by default (dir=f). Added a note
in tests to explain the differences in ordering.

Signed-off-by: Daniel Sonck <daniel@sonck.nl>