Add New Zealand Subdivision Aliases (EN, MI, HASC)

[PPsyrius]

Proposed change

Migrates deprecated New Zealand subdivisions to a new subdivision aliases system, and Maori names (ISO) and HASC 2-letter codes were added as optional aliases.

The "South Canterbury" subregion is undeprecated as they're still in active use as Regional Holiday Anniversaries: https://www.govt.nz/browse/work/public-holidays-and-work/public-holidays-and-anniversary-dates/ . As the New Zealand government never gave these territories any acronyms, the full name is getting used here. I'm not sure about its name, though; maybe a possible rename to "Canterbury (South)" to match the source above?

"Waitangi" is removed from the _deprecated_subdivisions list altogether as they're mistakenly added there in the first place in #608. It isn't remapped into any other subdivision at the moment, so they should be safe to remove here.

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/pin/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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (6ec8d56) to head (ff67f29).
Report is 2 commits behind head on dev.

Additional details and impacted files

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##               dev     #1952   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          188       188           
  Lines        11419     11400   -19     
  Branches      1795      1785   -10     
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- Hits         11419     11400   -19     

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[PPsyrius]

This should hopefully be the last PR for "_deprecated_subdivisions migration to subdivisions_aliases" right now unless I'm mistaken. 🙏

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[arkid15r]

@PPsyrius you've done a tremendous work migrating deprecated subdivisions to subdivisions aliases. Thank you!

I'm merging this as is for the next release so any other possible changes go in a separate PR(s).