Adding the threshold to the ROC curve hovertext

[freddyaboulton]

Pull Request Description

Fixes #1091 by displaying the threshold corresponding to each point in the ROC curve when the user hovers over the point. Before, the hovertext only included the x, y coordinate tuple, so I also added False Positive Rate and True Positive Rate as well to make it clearer. I can revert that change though since it's not mentioned in the original issue.

What it looks like to a user

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After creating the pull request: in order to pass the release_notes_updated check you will need to update the "Future Release" section of docs/source/release_notes.rst to include this pull request by adding :pr:123.

[codecov]

Codecov Report

Merging #1161 into main will increase coverage by 8.90%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1161      +/-   ##
==========================================
+ Coverage   91.00%   99.91%   +8.90%     
==========================================
  Files         197      197              
  Lines       11650    11653       +3     
==========================================
+ Hits        10602    11643    +1041     
+ Misses       1048       10    -1038     

Impacted Files	Coverage Δ
evalml/model_understanding/graphs.py	100.00% <100.00%> (+52.76%)	⬆️
...lml/tests/model_understanding_tests/test_graphs.py	100.00% <100.00%> (+42.59%)	⬆️
evalml/tests/component_tests/test_components.py	100.00% <0.00%> (+0.38%)	⬆️
evalml/automl/automl_search.py	99.58% <0.00%> (+0.41%)	⬆️
...s/prediction_explanations_tests/test_algorithms.py	100.00% <0.00%> (+1.11%)	⬆️
evalml/tests/component_tests/test_utils.py	100.00% <0.00%> (+3.57%)	⬆️
...derstanding/prediction_explanations/_algorithms.py	97.14% <0.00%> (+4.28%)	⬆️
evalml/tests/pipeline_tests/test_pipelines.py	100.00% <0.00%> (+4.86%)	⬆️
evalml/tests/utils_tests/test_dependencies.py	100.00% <0.00%> (+6.25%)	⬆️
evalml/utils/gen_utils.py	98.94% <0.00%> (+6.31%)	⬆️
... and 18 more

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[angela97lin]

🚢

[gsheni]

chart looks good!