Add UAE (United Arab Emirates) localflavor support

[samiashi]

Add UAE (United Arab Emirates) localflavor support

This PR adds complete localflavor support for the United Arab Emirates (UAE).

Form Fields:

• UAEEmiratesIDField - Validates 15-digit Emirates ID numbers in format 784-YYYY-NNNNNNN-N
• UAEEmirateField - Choice field for selecting from 7 UAE Emirates with 2-letter codes
• UAEEmirateSelect - Select widget with Emirates choices
• UAEPostalCodeField - Handles UAE's lack of postal codes (accepts "00000" or empty values)
• UAEPOBoxField - Validates P.O. Box numbers with flexible input formats
• UAETaxRegistrationNumberField - Validates 15-digit VAT registration numbers

Model Fields:

• Corresponding model fields for all form fields with appropriate max_lengths and validation

Additional Features:

• Arabic translations for Emirates names and validation messages
• Flexible input validation with automatic normalization
• Complete documentation following project standards
• Year-based validation for Emirates ID birth years

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All Changes

• Add an entry to the docs/changelog.rst describing the change.
• Add an entry for your name in the docs/authors.rst file if it's not already there.

New Fields Only

• Prefix the country code to all fields.
• Field names should be easily understood by developers from the target localflavor country. This means that English translations are usually not the best name unless it's for something standard like postal code, tax / VAT ID etc.
• Prefer 'PostalCodeField' for postal codes as it's international English; ZipCode is a term specific to the United States postal system.
• Add meaningful tests. 100% test coverage is not required but all validation edge cases should be covered.
• Add .. versionadded:: <next-version> comment markers to new localflavors.
• Add documentation for all fields.