Add multiplayer option to disable score multiplier

[timiimit]

This feature spans across osu, osu-server-spectator and osu-web projects. This should be merged only when all PRs are approved.

• [ ] Related: ppy/osu#23510

This PR adds a migration to add no_score_multiplier column to multiplayer_rooms table. I basically just followed how auto_skip was added in the past.