feat: add imports_fields option

[Boshen]

relates #135

[codspeed-hq]

CodSpeed Performance Report

Merging #138 will not alter performance

_{Comparing imports-fields (408cb0d) with main (675f5e3)}

Summary

✅ 2 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 85.36585% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 95.08%. Comparing base (675f5e3) to head (408cb0d).

Files	Patch %	Lines
src/lib.rs	79.16%	5 Missing ⚠️
src/options.rs	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #138      +/-   ##
==========================================
- Coverage   95.08%   95.08%   -0.01%     
==========================================
  Files          11       11              
  Lines        2238     2257      +19     
==========================================
+ Hits         2128     2146      +18     
- Misses        110      111       +1     

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