Add support for ICU library bundled with Windows

[rmisev]

This adds the cmake option variable UPA_USE_WINDOWS_ICU and a preprocessor macro of the same name for this purpose:

1. For cmake CLI add the option -DUPA_USE_WINDOWS_ICU=ON
2. Or define the preprocessor macro UPA_USE_WINDOWS_ICU = 1 if you are using amalgamated sources

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.65%. Comparing base (c9b7de4) to head (b71aca6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #49   +/-   ##
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  Coverage   99.65%   99.65%           
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  Files          16       16           
  Lines        2333     2333           
  Branches      387      387           
=======================================
  Hits         2325     2325           
  Misses          8        8           

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