fix: Improve contrast of completion popup in CloudEditor theme

[akoreman]

Issue #, if available: NA

Description of changes: Some parts of the default autocomplete popup did not meet accessibility contrast requirements, the gaps were:

• The blue completion highlight text has insufficient contrast with the selected and non-selected background, it should be 4.5:1.
• The blue completion highlight text has insufficient contrast with the 'normal' text, it should be 3:1.
• The light grey meta text on does not contrast 4.5:1 with the selected and non-selected background colors.

This improves the styling in our CloudEditor themes, which we use as our de-facto accessible themes.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (64101cc) 86.49% compared to head (1b3ebf9) 86.49%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5473   +/-   ##
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  Coverage   86.49%   86.49%           
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  Files         582      582           
  Lines       42355    42355           
  Branches     7055     7055           
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  Hits        36636    36636           
  Misses       5719     5719           

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unittests	86.49% <ø> (ø)

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[nightwing]

Can we make this specific for cloudEditor themes? Too high contrast does not look good with all themes, especially the ones that have low contrast intentionally.

[akoreman]

Can we make this specific for cloudEditor themes? Too high contrast does not look good with all themes, especially the ones that have low contrast intentionally.

As much as I'd like to argue that we should be accessible by-default I think I agree that this will look ugly with some themes and it will be annoying to users of those themes to expect them to style the completion popup back to what it was.

Since we are already using the CloudEditor themes as our de-facto accessible themes I added it to there.