Proposed change

Resolves #1825

Implements holidays date range functionality requested in #1825. It touches quite deep HolidayBase code (some refactoring plus a bunch of None values were provided where it wasn't expected), so please review carefully:

• Add HolidayBase::since and HolidayBase::until parameters
• Refactor types into a separate module
• Extract DateLike conversion to date to a separate module
• Update documentation with examples
• Fix specific observance logic cases for some countries
• Update test_utils::TestYears tests

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 run make pre-commit, it didn't generate any changes
• I've run make test, all tests passed locally