[FEATURE_REQUEST]: Support for code imports from non hook files

[miguelaeh]

We are loading the user code per hook file. This does not allow the user to split the code of a hook into multiple files.
It is a common and desired practice to separate utils functions from the "main" logic of the hook for readability, so we must support it.

[miguelaeh]

See: https://pyo3.rs/v0.20.0/python_from_rust#include-multiple-python-files