Add custom ArgoCD Yaml support

[mbaldessari]

Tested manually with
https://www.github.com/validatedpatterns/patterns-operator/pull/779 by
passing the following to values-global.yaml:

main:
  gitops:
    customArgoYaml: |
      controller:
        resources:
          limits:
            cpu: "4"
            memory: "17Gi"

Correctly obtained the ArgoCD instance with:

oc get -n vp-gitops argocd vp-gitops -o jsonpath='{.spec.controller.resources.limits}' | jq .
{
  "cpu": "4",
  "memory": "17Gi"
}