Split Matrix room creation into bare create and update all details function

Split Matrix room creation into bare create and update all details function

Fix #2686 (closed) and #2687 (closed)

Testing strategy

1. From Gitter, create a new room
2. From Gitter, send a message in that room
3. From Matrix, join the bridged room and notice all of the details are propagated over (room topic, avatar, set as public, etc)