This PR allows Synapse modules making use of the `ModuleApi` to create and send non-membership events into a room. This can useful to have modules send messages, or change power levels in a room etc. Note that they must send event through a user that's already in the room.
The non-membership event limitation is currently arbitrary, as it's another chunk of work and not necessary at the moment.
This commit has been cherry-picked from mainline.
This PR switches several conditions regarding room access rules to check against the status of the room's inclusion in the public room list instead of its join rules.
The code includes a snapshot of https://github.com/matrix-org/synapse/pull/8292, which will likely change in time and need merging in again.
Fixes https://github.com/matrix-org/synapse/issues/7683
Broke in: #7649
We had a `yield` acting on a coroutine. To be fair this one is a bit difficult to notice as there's a function in the middle that just passes the coroutine along.
