add visualization for kernels

[jmbhughes]

Close #223

[codecov]

Codecov Report

Attention: Patch coverage is 26.66667% with 11 lines in your changes missing coverage. Please review.

Project coverage is 86.92%. Comparing base (ca4ffb4) to head (2d63339).
Report is 20 commits behind head on main.

Files with missing lines	Patch %	Lines
regularizepsf/transform.py	27.27%	8 Missing ⚠️
regularizepsf/psf.py	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #225      +/-   ##
==========================================
- Coverage   87.78%   86.92%   -0.86%     
==========================================
  Files          12       12              
  Lines         884      895      +11     
==========================================
+ Hits          776      778       +2     
- Misses        108      117       +9     

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