Bring auto-accept invite logic into Synapse (#17147)

This PR ports the logic from the
[synapse_auto_accept_invite](https://github.com/matrix-org/synapse-auto-accept-invite)
module into synapse.

I went with the naive approach of injecting the "module" next to where
third party modules are currently loaded. If there is a better/preferred
way to handle this, I'm all ears. It wasn't obvious to me if there was a
better location to add this logic that would cleanly apply to all
incoming invite events.

Relies on https://github.com/element-hq/synapse/pull/17166 to fix linter
errors.

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/rest/client/utils.py b/tests/rest/client/utils.py

index fe00afe198..7362bde7ab 100644
--- a/tests/rest/client/utils.py
+++ b/tests/rest/client/utils.py
@@ -170,6 +170,7 @@ class RestHelper:
         targ: Optional[str] = None,
         expect_code: int = HTTPStatus.OK,
         tok: Optional[str] = None,
+        extra_data: Optional[dict] = None,
     ) -> JsonDict:
         return self.change_membership(
             room=room,
@@ -178,6 +179,7 @@ class RestHelper:
             tok=tok,
             membership=Membership.INVITE,
             expect_code=expect_code,
+            extra_data=extra_data,
         )
 
     def join(