standard color correction matrix function

[JorgeGtz]

Describe your changes Add a function that helps us access the standard rgb values (hard coded) for the chips in the color cards. This allow us to correct images with respect to the std values.

Source: https://en.wikipedia.org/wiki/ColorChecker

Type of update Is this a:

• New feature or feature enhancement
• Work in progress

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Additional context Add any other context about the problem here.

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• [ ] PR functionality reviewed in a Jupyter Notebook
• [ ] All tests pass
• [ ] Test coverage remains 100%
• [ ] Documentation tested
• [ ] New documentation pages added to plantcv/mkdocs.yml
• [ ] Changes to function input/output signatures added to updating.md
• [ ] Code reviewed
• [ ] PR approved

[codecov[bot]]

Codecov Report

Merging #931 (6595840) into release-4.0 (bf2093c) will not change coverage. The diff coverage is 100.00%.

@@              Coverage Diff              @@
##           release-4.0      #931   +/-   ##
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  Coverage       100.00%   100.00%           
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  Files              161       161           
  Lines             6844      6859   +15     
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+ Hits              6844      6859   +15     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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Impacted Files	Coverage Δ
plantcv/plantcv/transform/__init__.py	100.00% <100.00%> (ø)
plantcv/plantcv/transform/color_correction.py	100.00% <100.00%> (ø)