Introduce start/end year for entity

[KJhellico]

Proposed change

Introduce start/end year of period in which entity holidays are defined (with default values 1901 and 2100).

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 holidays functionality in general)

Checklist

• I've followed the contributing guidelines
• I've successfully run make check, all checks and tests are green

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (6a9735d) to head (c4b437f).

Additional details and impacted files

@@            Coverage Diff             @@
##               dev     #2141    +/-   ##
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  Coverage   100.00%   100.00%            
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  Files          194       194            
  Lines        11714     11556   -158     
  Branches      1772      1641   -131     
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- Hits         11714     11556   -158     

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[PPsyrius]

I'm glad this is finally getting implemented ❤️

This might be something for later, but having subdivision-level start dates would be nice for countries such as Australia or the United States - or a future #1852 implementation. 👀

[PPsyrius]

LGTM 🕚