Refactored Arabic Locale For Dehumanize Support

[anishnya]

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• 🧪 Added tests for changed code.
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Description of Changes

Refactor of Arabic Locale for future dehumanize support. The main reason for this change is that we need a way to convey the actual delta some of those strings represent. Rather than creating a look-up table, or some kind of translation logic, I think it is easier to just have the key be the string representation of an integer. This way, dehumanize call easily interpret this. This will make more sense, when I push the actual dehumanize update PR (after the backlog of locale refactor PRs get merged in :) ).

[codecov]

Codecov Report

Merging #1028 (8f4e1b6) into master (6b9e427) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #1028   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines         2161      2161           
  Branches       340       340           
=========================================
  Hits          2161      2161           

Impacted Files	Coverage Δ
arrow/locales.py	100.00% <100.00%> (ø)

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