Requires https://github.com/matrix-org/gomatrixserverlib/pull/376
This has numerous upsides:
- Less type casting to `*Event` is required.
- Making Dendrite work with `PDU` interfaces means we can swap out Event
impls more easily.
- Tests which represent weird event shapes are easier to write.
Part of a series of refactors on GMSL.
* Check state before event
* Tweaks
* Refactor a bit, include in output events
* Don't waste time if soft failed either
* Tweak control flow, comments, use GMSL history visibility type
* Specify interfaces used by appservice, do half of clientapi
* convert more deps of clientapi to finer-grained interfaces
* Convert mediaapi and rest of clientapi
* Somehow this got missed
* Generate m.room.canonical_alias instead of legacy m.room.aliases
* Add omitempty tags
* Add aliases endpoint to client API
* Check power levels when setting aliases
* Don't return null on /aliases
* Don't return error if the state event fails
* Update sytest-whitelist
* Don't send updated m.room.canonical_alias events
* Don't check PLs after all because for local aliases they are apparently irrelevant
* Fix some bugs
* Allow deleting a local alias with enough PL
* Fix some more bugs
* Update sytest-whitelist
* Fix copyright notices
* Review comments
