Correctly raise exceptions for ratelimitng. Ratelimit on 401

Implement /keys/changes

Add a small cache get_all_new_events

Only invalidate membership caches based on the cache stream

Add an index to make membership queries faster

Better handle 404 response for federation /send/

This is because it now relies of the caches stream, which only works on
postgres. We are trying to test with sqlite.

Before we completely invalidated get_users_in_room whenever we updated
any current_state_events table. This was way too aggressive.

Fix clearing out old device list outbound pokes

Use DB cache of joined users for presence

Device List fixes

Implement device lists updates over federation