Enumerate all the ways in which the wallet SQLite DB is used directly

[str4d]

We want to move all reads of the wallet SQLite DB behind the Rust FFI (to remove the current dependency on the SQL views). All places that currently read from the database directly will need to be replaced by backend calls.

To ensure that the new backend APIs expose the right functionality, we need to enumerate all the ways in which the SDK currently uses the SQLite database directly.