[Feature wish] when bridging matrix -> XMPP, use nickname set by `/myroomnick` (and avatar set by `/myroomavatar`) instead of global username or nickname.

Is your feature request related to a problem? Please describe.

I am part of a Matrix room which is bridged to an XMPP room.

In that Matrix room I set a specific display name with /myroomnick <specific_nickname>.
However, the XMPP side does receive messages from me not attributed to come from <specific_nickname>, but to come from the username part of my Matrix ID (or maybe from my globally set display name, they are the same).

This leads to inconsitencies how users reading the room via Matrix and users reading the room via XMPP perceive the messages, leading to confusion, because the same person appears as to be two different persons.

Describe the solution you'd like

Nickname on XMPP side equaling nickname on Matrix side.

(And actually the same with avatars.)

Describe alternatives you've considered

None, since I do not operate the bridge.

Regards!