Standardize documentation style with `darglint`

[cthoyt]

Summary

This PR adds the darglint plugin for flake8, whose job it is to check that documentation is provided in the correct format.

• [x] Unit tests provided for these changes
• [x] Documentation and docstrings added for these changes

Changes

• Add darglint to the flake8 environment in tox.ini
• Add darglint configuration in setup.cfg where I set sphinx as the preferred style for chemicalx. Previously, people looked towards the numpy and google styles since they helped reduce clutter, at the cost of taking a huge number of lines and leaving tons of dead whitespace. Now that type hints are first class in the python langauge, these formats seem a bit too verbose and the sphinx style is now best again
• Update all code to pass new tests

[codecov-commenter]

Codecov Report

Merging #70 (82ada2b) into main (a6f2b73) will increase coverage by 0.02%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #70      +/-   ##
==========================================
+ Coverage   93.74%   93.76%   +0.02%     
==========================================
  Files          29       29              
  Lines         815      818       +3     
==========================================
+ Hits          764      767       +3     
  Misses         51       51              

Impacted Files	Coverage Δ
chemicalx/data/batchgenerator.py	98.30% <ø> (ø)
chemicalx/data/contextfeatureset.py	100.00% <ø> (ø)
chemicalx/data/drugfeatureset.py	100.00% <ø> (ø)
chemicalx/data/labeledtriples.py	100.00% <ø> (ø)
chemicalx/models/deepsynergy.py	100.00% <ø> (ø)
chemicalx/models/epgcnds.py	100.00% <ø> (ø)
chemicalx/models/matchmaker.py	95.00% <ø> (ø)
chemicalx/data/datasetloader.py	87.23% <100.00%> (+0.27%)	:arrow_up:

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