fix(legend): disable fade other if legend item is not visible

[markov00]

Summary

When hovering on a legend item that is currently hidden, don't fade the other series https://d.pr/free/i/DbbyWC

TODO

The current status correctly avoid hiding the other series when mouse over an hidden one:

What is missing is the following: fade in all the series right after I clicked a series in the legend. Currently, if you click to hide a series, the rendered series are in a fade status. We need to have a consistent behaviour and, right after a click I just want to hide the clicked series and also I want to see all the other clearly

wrong behaviour

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

• Any consumer-facing exports were added to src/index.ts (and stories only import from ../src except for test data & storybook)
• This was checked for cross-browser compatibility, including a check against IE11
• Proper documentation or storybook story was added for features that require explanation or tutorials
• Unit tests were updated or added to match the most common scenarios
• Each commit follows the convention

[codecov-io]

Codecov Report

Merging #321 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #321      +/-   ##
==========================================
+ Coverage   98.04%   98.05%   +<.01%     
==========================================
  Files          37       37              
  Lines        2715     2719       +4     
  Branches      636      638       +2     
==========================================
+ Hits         2662     2666       +4     
  Misses         48       48              
  Partials        5        5

Impacted Files	Coverage Δ
src/chart_types/xy_chart/store/chart_state.ts	96.91% <100%> (+0.02%)	⬆️

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[nickofthyme]

@markov00 Did you want to add anything more to this PR?