feat(isMobilePhone): add en-KY and en-BB mobile phone locales

[pratik1258m]

This PR adds mobile phone number validation support for two missing English-speaking Caribbean territories under the North American Numbering Plan (+1):

• Cayman Islands (en-KY): Validates the 345 area code.
• Barbados (en-BB): Validates the 246 area code.

References:

• Cayman Islands mobile phone format: +1 (345) XXX-XXXX (ITU-T E.164 Recommendation, NANPA)
• Barbados mobile phone format: +1 (246) XXX-XXXX (ITU-T E.164 Recommendation, NANPA)

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable)
• Tests written (where applicable)
• References provided in PR (where applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (7fdc788) to head (f9c5147).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2716   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          114       114           
  Lines         2587      2587           
  Branches       656       656           
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  Hits          2587      2587           

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