Adds prototype spark caching code

[skrawcz]

I haven't tested this, but this I think should be
good enough to try things, you'd just want to
annotate what you want.

To use, you'd just need to pass in the spark session to the read_kwargs argument of the constructor as "spark_session" for being able to read back things.

Changes

• h_cache

How I tested this

• I haven't

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.