Python: support Operations defined in Python

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 89.21569% with 11 lines in your changes are missing coverage. Please review.

Project coverage is 87.22%. Comparing base (7d7a5d3) to head (6ca880e). Report is 4 commits behind head on master.

Files	Patch %	Lines
python/src/pybindings/operation_bindings.cpp	90.38%	5 Missing :warning:
python/src/exactextract/exact_extract.py	88.46%	3 Missing :warning:
python/src/pybindings/feature_bindings.cpp	82.35%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #88 +/- ## ========================================== - Coverage 87.59% 87.22% -0.37% ========================================== Files 68 68 Lines 3709 3813 +104 ========================================== + Hits 3249 3326 +77 - Misses 460 487 +27 ```

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[dbaston]

Merged in 33eb94b6a26d9a315d2f0dba283a11b6382c911f