feat: add i18n support for itemRemovedAriaLive in attribute-editor

[Harsh-Anand-Singh]

Description

This PR provides the itemRemovedAriaLive string for AttributeEditor via the i18n provider, reducing friction for customers who previously had to manually provide this label.

The solution merges translated strings from the AWS-UI-Components-I18n package and provides the default announcement when no custom value is specified, while still allowing overrides through the i18nStrings prop. Additionally, the i18nStrings property documentation has been improved to clearly list all available localized strings with descriptions.

Related links, issue #, if available: AWSUI-61133

How has this been tested?

I've tested the i18n integration:

• Modified the attribute-editor simple page locally to wrap the component with I18nProvider to enable i18n functionality
• Verified that the component without explicit itemRemovedAriaLive now receives the default i18n value
• Confirmed that explicit i18nStrings.itemRemovedAriaLive values continue to override the default
• Tested with a screen reader to verify the removal announcement is properly announced
• Verified the i18n integration works correctly by adding unit tests

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.19%. Comparing base (05d1e35) to head (63a7cd8).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

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##             main    #3985   +/-   ##
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  Coverage   97.18%   97.19%           
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  Files         858      858           
  Lines       25345    25350    +5     
  Branches     9004     9007    +3     
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+ Hits        24632    24638    +6     
+ Misses        664      663    -1     
  Partials       49       49           

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