Previously we made them using the offset Kafka supplied.
We don't run Kafka anymore, so now we make the SQL table assign
the change ID via an AUTOINCREMENTing ID. Redesign the
`keyserver_key_changes` table to have `UNIQUE(user_id)` so we
don't accumulate key changes forevermore, we now have at most 1
row per user which contains the highest change ID.
This needs a SQL migration.
This was used by the device list stream position. The device list position
now corresponds to the `Offset`, and the partition is always 0, in prep
for removing reliance on Kafka topics for device list changes.
* Recheck device lists when join/leave events come in
* Add PerformDeviceDeletion
* Notify clients when devices are deleted
* Unbreak things
* Remove debug logging
* Persist partition|offset|user_id in the keyserver
Required for a query API which will be used by the syncapi which
will be called when a `/sync` request comes in which will return
a list of user IDs of people who have changed their device keys
between two tokens.
* Add tests and fix maxOffset bug
* s/offset/log_offset/g because 'offset' is a reserved word in postgres
* Produce kafka events when keys are added
* Consume key changes in syncapi with TODO markers for handling them and catching up
* unbreak tests
* Linting
