feat(py): caching support

[cmdoret]

Exposes caching helpers to the python API.

This also improves error handling throughout the library by returning Result instead of panicking.

Context:

Many (not so) edge cases resulted in panics, because we use the anyhow crate to handle errors, and I did not know how to convert its Results to PyErr in the python bindings. Turns out there's an optional anyhow feature in the PyO3 crate to auto-cast Results.

Changes Summary:

• Propagate results throughout fuzon all the way to the python library.
• Expose caching helpers from rust to python.
• Improve documentation in the python library.

[gabyx]

Well done!
Only a few nitpicks.
However the granular caching suggestion (why you didnt go that way) probably has a reason I am curious to find out!