We add sqlite.proto and define interfaces to access this from rslib-bridge

(cherry picked from commit 6d5d150)

This works for all but open/closeBackend. This is because we currently return
raw values rather than protobuf byte streams.

This is WIP as the Rust could be implemented better - possibly a macro

A function was attempted and should be tried again with a single lambda
Multiple parameters made execution significantly slower.

But, learning how to do macros can wait until the library is released.

(cherry picked from commit 8cb83f4)

The anki crate should expose these as features in the future.

- Reuses existing protobuf infrastructure to greatly cut down on the
JNI boilerplate
- Ensures all calls have errors handled, and happen behind a mutex
- Removes separate downgrade + open11 calls in favour of a flag to
the standard collection opening routine
- Various code cleanups