Fix Kubernetes file compare issue with empty documents

[HeavyWombat]

• Add implicit managedFields exclude
• Omit empty documents in Kubernetes compare

@dalbar FYI

[codecov]

Codecov Report

Merging #224 (98392c7) into main (16e0fd6) will increase coverage by 0.29%.
The diff coverage is 95.65%.

❗ Current head 98392c7 differs from pull request most recent head 40ba8c6. Consider uploading reports for the commit 40ba8c6 to get more accurate results

@@            Coverage Diff             @@
##             main     #224      +/-   ##
==========================================
+ Coverage   81.84%   82.14%   +0.29%     
==========================================
  Files          13       13              
  Lines        1289     1305      +16     
==========================================
+ Hits         1055     1072      +17     
  Misses        173      173              
+ Partials       61       60       -1     

Flag	Coverage Δ
unittests	82.14% <95.65%> (+0.29%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/dyff/core.go	88.12% <95.45%> (+0.14%)	⬆️
internal/cmd/root.go	91.42% <100.00%> (+0.25%)	⬆️
internal/cmd/between.go	86.04% <0.00%> (+4.65%)	⬆️

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