* WIP: Eagerly sync device lists on /user/keys/query requests
Also notify servers when a user's device display name changes. Few
caveats:
- sytest `Device deletion propagates over federation` fails
- `populateResponseWithDeviceKeysFromDatabase` is called from multiple
goroutines and hence is unsafe.
* Handle deleted devices correctly over federation
* Add InputDeviceListUpdate
* Unbreak unit tests
* Process inbound device list updates from federation
- Persist the keys in the keyserver and produce key changes
- Does not currently fetch keys from the remote server if the prev IDs are missing
* Linting
* Add QueryDeviceMessages to serve up device keys and stream IDs
* Consume key change events in fedsender
Don't yet send them to destinations as we haven't worked them out yet
* Send device list updates to all required servers
* Glue it all together
* Recheck device lists when join/leave events come in
* Add PerformDeviceDeletion
* Notify clients when devices are deleted
* Unbreak things
* Remove debug logging
* Add storage layer for postgres/sqlite
* Return OTK counts when inserting new keys
* Hook up the key DB and make a test pass
* Convert postgres queries to be sqlite queries
* Blacklist test due to requiring rejected events
* Unbreak tests
* Update blacklist
