- use `appdatabse.DbInitializer{}` in tests to ensure consistent migrations
- remove protocol's open database functions due to improper
initialization caused by missing node config migration
- introduce `PushNotificationServerConfig` to resolve cyclic dependency
issues
interface for initializing db, which is implemented for appdatabase and
walletdatabase. TBD for multiaccounts DB.
Unified DB initializion for all tests using helpers and new interface.
Reduced sqlcipher kdf iterations for all tests to 1.