Delete local RoomAccessRules module

[babolivier]

The two features implemented by this module now live in https://github.com/vector-im/synapse-room-access-rules and https://github.com/matrix-org/synapse-freeze-room

Note to ops:

To deploy this change, the modules need to be installed in addition to Synapse (from the aforementioned repos, or the PyPI project mentioned in their readmes). The configuration for each individual module doesn't change besides a) being split between two modules and b) needing to be moved to the modules section of the config file, e.g.:

modules:
    - module: freeze_room.FreezeRoom
      config: ...
    - module: room_access_rules.RoomAccessRules
      config: ...

[clokep]

Looks like this deletes only files which aren't in mainline Synapse. I believe the modules were already checked to ensure they implement the same behavior.