cherry-pick Add unit tests for health & application set status to release-4.18 branch

[aali309]

Cherry-pick of: #290 to release-4.18 branch

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (release-4.18@610a68f). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...rc/gitops/components/shared/ApplicationSetList.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##             release-4.18     #298   +/-   ##
===============================================
  Coverage                ?   12.76%           
===============================================
  Files                   ?      172           
  Lines                   ?     6839           
  Branches                ?     2309           
===============================================
  Hits                    ?      873           
  Misses                  ?     5960           
  Partials                ?        6           

Flag	Coverage Δ
unit-tests	12.76% <93.33%> (?)

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[keithchong]

LGTM. Same as main. Thanks @aali309 . FYI, @trdoyle81