Add special holidays per subdivisions support

[KJhellico]

Proposed change

Add special holidays per subdivisions support: e.g., special_bc_public_holidays (with categories support) or special_qld_holidays (without).

Refactor Australia and Canada holidays as example.

Type of change

• New country/market holidays support (thank you!)
• Supported country/market holidays update (calendar discrepancy fix, localization)
• Existing code/documentation/test/process quality improvement (best practice, cleanup, refactoring, optimization)
• Dependency update (version deprecation/upgrade)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (a code change causing existing functionality to break)
• New feature (new python-holidays functionality in general)

Checklist

• I've followed the contributing guidelines
• I've added references to all holidays information sources used in this PR
• The code style looks good: make pre-commit command generates no changes
• All tests pass locally: make test, make tox (we strongly encourage adding tests to your code)

[arkid15r]

It's a nicely implemented refactoring! 👏

The business logic hasn't changed (thank goodness we have tests/snapshots) whereas readability and flexibility has raised drastically.

My comments and method naming suggestions:

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[arkid15r]

LGTM