m.room.create
events have a mandatory creator property giving the ID of the user who
created the room. This field is redundant as it is always identical to the
sender of the create event.
This MSC proposes that, in a future room version, this field should be removed
and that the sender field be used instead.
Note that creator is mentioned in the auth
rules. It can
safely be replaced with a check against the sender instead.
creator is also mentioned as a key to be preserved during Event
redaction. It
should be removed from that list.