Add plot functionality to AUROC and ROC metrics

[alexkrz]

What does this PR do?

Fixes part of #1406

Currently, plot functionality is added to modular metrics BinaryAUROC, MulticlassAUROC, MultilabelAUROC and BinaryROC.

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• Did you make sure to update the docs?
• Did you write any new necessary tests?

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[alexkrz]

Not sure why the docs test is failing. Docs could be build successfully on my local machine.
Also one question: I have adopted the examples from the MulticlassAccuracy metric and I am using random numbers for preds and target. Is there a fixed seed such that the examples generated in the docs turn out the same on every build?

[SkafteNicki]

Already looking good :)
Could you please also add test to this file:
https://github.com/Lightning-AI/metrics/blob/master/tests/unittests/utilities/test_plot.py

[alexkrz]

Already looking good :) Could you please also add test to this file: https://github.com/Lightning-AI/metrics/blob/master/tests/unittests/utilities/test_plot.py

This is actually my first time contributing to an open source project and I am new to working with pytest. I have now included tests for BinaryAUROC and MulticlassAUROC plots. I would be glad if you could have a look on it.
I can also try to write a test for the plot_binary_roc_curve() function from src/utilities/plot.py

[codecov]

Codecov Report

Merging #1490 (fc4b1c9) into master (82d5271) will decrease coverage by 0%.
The diff coverage is 56%.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1490   +/-   ##
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- Coverage      88%     88%   -0%     
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  Files         216     216           
  Lines       11344   11396   +52     
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+ Hits         9969    9997   +28     
- Misses       1375    1399   +24