* Add `QueryRestrictedJoinAllowed`
* Add `Resident` flag to `QueryRestrictedJoinAllowedResponse`
* Check restricted joins on federation API
* Return `Restricted` to determine if the room was restricted or not
* Populate `AuthorisedVia` properly
* Sign the event on `/send_join`, return it in the `/send_join` response in the `"event"` key
* Kick back joins with invalid authorising user IDs, use event from `"event"` key if returned in `RespSendJoin`
* Use invite helper in `QueryRestrictedJoinAllowed`
* Only use users with the power to invite, change error bubbling a bit
* Placate the almighty linter
One day I will nuke `gocyclo` from orbit and everything in the world will be much better for it.
* Review comments
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