Fixes include:
- Translating state keys that contain user IDs to their respective room
keys for both querying and sending state events
- **NOTE**: there may be design discussion needed on what should happen
when sender keys cannot be found for users
- A simple fix for kicking guests from rooms properly
- Logic for boundary history visibilities was slightly off (I'm
surprised this only manifested in pseudo ID room versions)
Signed-off-by: `Sam Wedgwood <sam@wedgwood.dev>`
Replaced with types.HeaderedEvent _for now_. In reality we want to move
them all to gmsl.Event and only use HeaderedEvent when we _need_ to
bundle the version/event ID with the event (seriailsation boundaries,
and even then only when we don't have the room version).
Requires https://github.com/matrix-org/gomatrixserverlib/pull/373
