vega: templates: make confusion matrix interactive

[pared]

Introducing interactivity to confusion matrix.
example
(hover over confusion matrix to see the effect).

Ideally we would also like to have ability to see number of actual vs number of predicted when hovering over it.
I will play around with this PR and see how hard that can be. If i wont find quick solution, I will create issue for that.

[codecov-commenter]

Codecov Report

Merging #45 (46dc455) into main (28c1495) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #45   +/-   ##
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  Coverage   95.68%   95.68%           
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  Files          14       14           
  Lines         464      464           
  Branches       76       76           
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  Hits          444      444           
  Misses         15       15           
  Partials        5        5           

Impacted Files	Coverage Δ
src/dvc_render/vega_templates.py	97.95% <ø> (ø)

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[shcheklein]

@pared looks good, thanks. Tooltip with actual numbers would be great to have!

[pared]

@shcheklein my bad, what I was discussing with @mnrozhkov was to show a tooltip with actual {class} and predicted {class}. Added the tooltip.
After the modification the confusion matrix will look as follows
Anyway, we can add other fields too.

[mnrozhkov]

Tooltip with actual numbers would be great to have!

Thanks @pared ! Looks good for me! It's very helpful for matrix with many classes!
@shcheklein usually confusion matrix contains numbers of classes in each cell (not ratio). So,Tooltip with actual numbers is not necessary.

[pared]

@mnrozhkov I think the confusion started from me not understanding our discussion, only reading it today made me realize what you need :)