[ENH]: use Rust HTTP server in Python tests

[codetheweb]

Description of changes

Updates the Python test suite to remove Python SQLite-based test fixtures and adds test fixtures for testing against the Rust HTTP server. A few tests were not previously running against the Rust HTTP server.

Also makes a few adjustments to the Rust side to allow starting an ephemeral server.

Test plan

How are these changes tested?

• [x] Tests pass locally with pytest for python, yarn test for js, cargo test for rust

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs repository?

n/a