Remove it from request handler since there's already the context of the
request path, added through TraceLayer.

They are no longer needed in the 2021 edition.

Co-authored-by: Timo Kösters <timo@koesters.xyz>

this also reverts some stateres changes

TIL body.device_id != (*body).device_id, which is pretty bad, so I
renamed body.device_id to body.sender_device

They are not in the spec and maubot relies on that

The 404 error for /profile in the spec says "There is no profile
information for this user or this user does not exist.", but Element
assumes every 404 is a user that does not exist.