Reconsider changing of database

[BarkingBad]

Currently we have 2 redundant models defined in commonKotlin and commonScala. We should reconsider getting one model of database, ideally originating from commonScala. Maybe we should change json format to protobuf using ScalaPB

[KacperFKorban]

The part about redundant models isn't relevant anymore, but changing the format may be needed in the future.