feat: ensure plugin removal during Helm uninstall

[TylerGillson]

Fixes #108. Use spectro-cleanup to delete the ValidatorConfig CR first, which ensures that validator garbage collects all installed plugins prior to Helm deleting validator.

@karl-cardenas-coding the user will still need to execute kubectl delete namespace validator, as Helm does not remove the release namespace during helm uninstall. See helm/helm#1464.

[codecov]

Codecov Report

Merging #111 (cb4e86a) into main (855e70e) will increase coverage by 0.37%.
The diff coverage is 66.66%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #111      +/-   ##
==========================================
+ Coverage   44.69%   45.06%   +0.37%     
==========================================
  Files           9        9              
  Lines         810      801       -9     
==========================================
- Hits          362      361       -1     
+ Misses        425      417       -8     
  Partials       23       23              

Files	Coverage Δ
internal/controller/validatorconfig_controller.go	73.71% <100.00%> (+0.68%)	⬆️
internal/controller/validationresult_controller.go	72.72% <50.00%> (+4.64%)	⬆️

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[mattwelke]

LGTM. I can see that cleanup is a tool which deletes k8s resources according to a config file that it expects to be at a particular path. Here, we put the config for what to delete into a ConfigMap and mount it to the pod that will be doing the cleanup, so that it knows what to delete.