While there are a lot of changes, the most significant are:
- Update the main entrypoint of the SDK to use a suspending function and eliminate lazy initialization. This also resolves#310
- Changing Dao methods to `suspend`, allowing Room to implicitly manage the threading model under the hood
- Explicitly set the executor thread for the `CompactBlockDb` and `DerivedDataDb`, which is the same thread used when calling into the Rust native library. Room will then use this thread for `suspend` fun calls into it
- With the above set, remove unnecessary hops to Dispatchers.IO which is a thread pool
- Eliminate lazy initialization in `PagedTransactionRepository` to make it easier to reason about the threading model and resolve#355 where the database was being touched from the UI thread
Note that `PendingTransactionsDb` is not opted into this single-threaded approach, because that database is not shared with the Rust code