Add code syntax highlight utils

[Czaki]

This PR adds code syntax highlight first introduced in https://github.com/napari/napari/pull/4414

[codecov[bot]]

Codecov Report

Merging #88 (1619ed9) into main (cc25733) will increase coverage by 0.28%. The diff coverage is 98.00%.

@@            Coverage Diff             @@
##             main      #88      +/-   ##
==========================================
+ Coverage   84.58%   84.86%   +0.28%     
==========================================
  Files          29       30       +1     
  Lines        2329     2379      +50     
==========================================
+ Hits         1970     2019      +49     
- Misses        359      360       +1     

Impacted Files	Coverage Δ
src/superqt/utils/_code_syntax_highlight.py	97.95% <97.95%> (ø)
src/superqt/utils/__init__.py	100.00% <100.00%> (ø)

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[tlambert03]

thanks!