Make GraphemeCategory enum tree-shakable

[cometkim]

GraphemeCategory enum is not used internally, but is exported as a utility for advanced use cases.

Modern bundlers could optimize (DCE) if user don't use it.

However, I noticed that it is included in the Bluesky's webpack bundle. It's a 147 bytes of dead code.

Maybe I need to avoid the barrel file pattern, and to make it separated API such as `unicode-segmenter/grapheme-util'?

[changeset-bot]

⚠️ No Changeset found

Latest commit: 64e0c59

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[codspeed-hq]

Merging this PR will not alter performance

Summary

✅ 6 untouched benchmarks

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_{Comparing tree-shake-categories (64e0c59) with main (4443501)}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (e50d821) to head (64e0c59).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #119   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
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  Files           10        11    +1     
  Lines          951       902   -49     
=========================================
- Hits           951       902   -49     

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