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.
* Update sync responses
* Fix positions, add ApplyUpdates
* Fix MarshalText as non-pointer, PrevBatch is optional
* Increment by number of read receipts
* Merge branch 'master' into neilalexander/devicelist
* Tweak typing
* Include keyserver position tweak
* Fix typing next position in all cases
* Tweaks
* Fix typo
* Tweaks, restore StreamingToken.MarshalText which somehow went missing?
* Rely on positions from notifier rather than manually advancing them
* Revert "Rely on positions from notifier rather than manually advancing them"
This reverts commit 53112a62cc3bfd9989acab518e69eeb27938117a.
* Give invites their own position, fix other things
* Fix test
* Fix invites maybe
* Un-whitelist tests that look to be genuinely wrong
* Use real receipt positions
* Ensure send-to-device uses real positions too
* 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
