Switch from Isar to Drift for Caching

[jakobkoerber]

It seems like IsarDB is not really maintained anymore by the creator and with V4 not being ready for production and V3 having multiple crucial bugs a switch to a different DB solution is needed. Drift provides a Dart Wrapper around SQLite, is actively maintained and developed and relies on known DB solutions

• [ ] implement support for our gRPC Client (async calls are bit flaky or possibly impossible)