Add programmatic label and focus indicator to PIN entry field

[bmarty]

Summary

• Adds a programmatic contentDescription to PinEntryTextField's BasicTextField so TalkBack announces the field label and how many digits have been entered (fixes A11y: [Choose PIN] PIN input fields lack programmatically associated ... #6391)
• Adds a visible 2dp keyboard focus border (using ElementTheme.colors.borderInteractiveHovered) to PinEntryRow when the field has focus (fixes A11y: [Choose PIN] PIN input field has no visible keyboard focus indi... #6401)

The current digit will have an highlight border:

Test plan

• Open the PIN setup/entry screen with TalkBack enabled — verify the field is announced as "PIN field, N digit(s) entered"
• Navigate to the PIN field with a keyboard — verify a visible focus border appears around the digit row

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.55%. Comparing base (58b3830) to head (bad39d6).
⚠️ Report is 100 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7132   +/-   ##
========================================
  Coverage    80.54%   80.55%           
========================================
  Files         2689     2689           
  Lines        76433    76448   +15     
  Branches     10291    10291           
========================================
+ Hits         61566    61582   +16     
  Misses       10933    10933           
+ Partials      3934     3933    -1     

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[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[ganfra]

Is it provided by design? Looks like we don't see the border color in Light them?

[bmarty]

@gaelledel I have made a proposal in this PR, can you validate that it's fine for you? The current to-be-entered digit has a border color borderFocused (see the screenshot in the PR description).

@ganfra the preview is not reliable, but it works in light theme in the app.