Implement SPORF in ProgLearn: fit function, recreate SPORF figures

[parthgvora]

The end goal is to create an sklearn compliant SPORF in proglearn that is modular enough to add different kinds of oblique trees in the future (i.e. MORF). This issue is in tandem with #352

1. Implement fit function
2. Write unit tests for fit function
3. Recreate figures from SPORF paper with sklearn SPORF implementation
4. Feature request for sklearn oblique trees: write "Describe your proposed workflow" section

[parthgvora]

Please assign @parthgvora this issue

[levinwil]

Closing, per PR #374

[PSSF23]

Reopen until performance and correctness verified with paper figures