feat: Add MacAddressRecognizer

[kyoungbinkim]

Change Description

Adds support for detecting MAC (Media Access Control) addresses as a new global PII entity type. This recognizer supports three industry-standard MAC address formats commonly used across network devices and documentation.

• Colon-separated: 00:1A:2B:3C:4D:5E (IEEE 802 standard)
• Hyphen-separated: 00-1A-2B-3C-4D-5E (Windows format)
• Cisco dot-separated: 0012.3456.789A (Cisco IOS format)

Changes Made

• Added MacAddressRecognizer in presidio_analyzer/predefined_recognizers/generic/
• Pattern-based detection with 0.6 base confidence score
• Context-aware scoring using keywords: mac, mac address, hardware address, physical address, ethernet
• Validation logic to reject invalid formats and broadcast addresses (FF:FF:FF:FF:FF:FF)
• Registered recognizer in predefined_recognizers/__init__.py
• Updated docs/supported_entities.md with new MAC_ADDRESS entity type
• Comprehensive test suite with 15 test cases covering all formats and edge cases

Checklist

• I have reviewed the contribution guidelines
• I have signed the CLA (if required)
• My code includes unit tests
• All unit tests and lint checks pass locally
• My PR contains documentation updates / additions if required