Support new API's to block and unblock rooms

[JOJ0]

One new subcommand to block and unblock rooms: https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#block-or-unblock-a-room

One new subcommand to query blocking status: https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#get-block-status

Make sure when issued on pre-1.48. Synapse, synadm prevents issuing these API calls.