Support GTIN-8 prefixes assigned to UK and Poland

[jodal]

To make these exceptions possible to encode, the internal data structure for GS1 Prefixes was changed from using a list of prefix ranges to using a prefix trie, like the GS1 Company Prefix implementation already uses.

Fixes #162

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (c93de98) to head (bfa4d39).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #384   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           15        15           
  Lines         1061      1059    -2     
  Branches       106       106           
=========================================
- Hits          1061      1059    -2     

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