* Remove QueryBulkStateContent from current state server
Expected fail due to db impl not existing
* Implement query bulk state content
* Fix up rejecting invites over federation
* Fix bulk content marshalling
* Move currentstateserver API to roomserver
Stub out DB functions for now, nothing uses the roomserver version yet.
* Allow it to startup
* Implement some current-state-server storage interface functions
* Add missing package
* Add Queryer and use embedded structs
* Add Inputer and factor out more RS API stuff
This neatly splits up the RS API based on the functionality it provides,
whilst providing a useful place for code sharing via the `helpers` package.
