Room/MUC should have the same Room rights as the bridged Room

[JokerGermany]

Describe the bug
When i have a Matrix room where only Moderators/Admins can write, XMPP-Usern shouldn't be able to write as well.

To Reproduce

1. Create a Matrix Room where only Moderators/Admins can write
2. join it with a XMPP Account.
3. you can write messages which won't be bridged to the Matrix-Room but can be seen by other XMPP-Users.

Expected behavior
The XMPP/Matrix rights should be nearly* the same
(* as far as possible. e.G. when a XMPP User joins a Matrix Room where only Moderators and Admins are allowed to join, then a moderated MUC should be created.)

Additional context
Perhaps a quick and dirty solution for Moderated Rooms/MUC could be allowing to write, but if the other bridged MUC/Room "reject" the message, it get deleted in the Gateway-Room/MUC aswell.

[Neustradamus]

To follow the ticket, thanks @JokerGermany!