make all bandwidth saving options toggleable in one centralized server config

multitab protection mode
- allowed
- verified only
- not allowed
snapshots
- non-turn snapshots
  - on (you see snapshots when its not your turn)
  - off (everyone gets full video all the time)
- non-local spectator snapshots
  - on (external spectators are only allowed snapshots)
  - off (all spectators get full video)
external spectator access (new)
- off (no one can access the spectate page externally)
- on (everyone can access the spectate page externally)
anything else related to bandwidth savings should also get config