Add country calling codes enum

[PrinsFrank]

closes #7

[codecov-commenter]

Codecov Report

Merging #32 (42576f6) into main (642bf01) will not change coverage. The diff coverage is n/a.

@@             Coverage Diff             @@
##                main       #32   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity        48        48           
===========================================
  Files             13        13           
  Lines             97        97           
===========================================
  Hits              97        97           

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