In other messaging applications (e.g. Discord) this is possible through
text modifiers like "from:@user". We don't support that, and I'm not
super keen on implementing yet-another-parsing-thing, so an action in
the user detail dialog should work for now.
Very useful to sift through large rooms but when you only care about a
specific person's messages (maybe your own?)
Create a new module for the room info drawer QML. This also requires moving some QML to LibNeoChat common with other modules. Finally all QML in roominfo is modifed to not depend on app.