Set schema export directory for room

[Supercaly]

At the moment android studio gives this warning:

Values of variant API AnnotationProcessorOptions.arguments are queried and may return non final values, this is unsupported
/Users/lorenzo/AndroidStudioProjects/HandMonitor/wear/build/tmp/kapt3/stubs/release/com/handmonitor/wear/database/AppDatabase.java:22: warning: Schema export directory is not provided to the annotation processor so we cannot export the schema. You can either provide `room.schemaLocation` annotation processor argument OR set exportSchema to false.
public abstract class AppDatabase extends androidx.room.RoomDatabase {

Investigate if we need to export the schema or set exportSchema to false