PLAT-75858: Adjust focus timing when ContextualPopup is closed with a 'back' button

[Baekwoo-s]

Checklist

• [x] I have read and understand the contribution guide

• [x] A CHANGELOG entry is included

• [ ] At least one test case is included for this feature or bug fix

• [x] Documentation was added or is not needed

• [ ] This is an API breaking change

Issue Resolved / Feature Added

A11y issue when closing the ContextualPopup by pressing the back button on the remote control

• The TV must read 'back' + 'activator button contents' but reads the 'activator button contents' before finishing to read 'back'. (Sometimes it reads 'B'(part of 'Back') + 'activator button contents' button')

Resolution

• Modified to defer reading activator button contents about 800 ms by adding aria-hidden attribute to prevent reading 'back' from canceling
• Added activatorAriaHidden state to prevent the activator from read-out

Additional Considerations

• Why set 800ms for setTimeout: The activator should not be focussed while reading 'back'. In less than 800ms, reading 'back' is interrupted.
• I tested this for a11y read speed set to medium. But I don't know if this figure will cover all cases.

[codecov[bot]]

Codecov Report

Merging #2166 into develop will decrease coverage by 0.02%. The diff coverage is 0%.

@@            Coverage Diff             @@
##           develop   #2166      +/-   ##
==========================================
- Coverage    45.52%   45.5%   -0.03%     
==========================================
  Files          247     247              
  Lines         9684    9689       +5     
  Branches      2432    2433       +1     
==========================================
  Hits          4409    4409              
- Misses        3874    3878       +4     
- Partials      1401    1402       +1

Impacted Files	Coverage Δ
...ntextualPopupDecorator/ContextualPopupDecorator.js	0% <0%> (ø)	:arrow_up:

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[Baekwoo-s]

@0x64 I have all modified. Thanks.

[0x64]

Note: this PR is not a solution for the root cause but a kind of workaround.

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