[feature/alt-session-storage] Fix Redis storage functions

Debug and fix various problems with the Redis storage
to pass the session storage tests.

PHPBB3-11705
[feature/alt-session-storage] Obtain online test use storage

PHPBB3-11705
[feature/alt-session-storage] Fix Redis storage get_user_online_totals

PHPBB3-11705
[feature/alt-session-storage] Move friends function over to db_session

PHPBB3-11705
[feature/alt-session-storage] Fix native storage being used as db.

PHPBB3-11705