Implement migration logic for old database

[DRSchlaubi]

We need to migrate from Cassandra to mongo

[Niggelgame]

what data exactly should be migrated?
e. g. current polls won't work anyways

[DRSchlaubi]

Oh wow didn't think of that. We could make old polls work but not all of them and also it would not be worth the effort.
But we can migrate settings

[yk-sgr]

Prolly write a short Kotlin script that does this

[DRSchlaubi]

Obviously I gotta write a kotlin script