fix: adding persian names of months and month-abbreviations and day-abbreviations in Gregorian calendar

[fouladi]

Pull Request Checklist

Thank you for taking the time to improve Arrow! Before submitting your pull request, please check all appropriate boxes:

• 🧪 Added tests for changed code.
• 🛠️ All tests pass when run locally (run tox or make test to find out!).
• 🧹 All linting checks pass when run locally (run tox -e lint or make lint to find out!).
• 📚 Updated documentation for changed code.
• ⏩ Code is up-to-date with the master branch.

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Description of Changes

[jadchaar]

@fouladi would it be possible to add some unit tests? Then we can merge this in.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (403c29f) to head (cd6db81).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1172   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines         2324      2324           
  Branches       357       357           
=========================================
  Hits          2324      2324           

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[jadchaar]

Any reason why you added the + signs? These are unnecessary. Mind removing them in a revision so we can merge these changes in?

[jadchaar]

Once plus signs are removed and unit tests are added we can merge.