feat(argocd-apps): Support Template Patch to ApplicationSet

[yu-croco]

Resolves #2463

Checklist:

• I have bumped the chart version according to versioning
• I have updated the documentation according to documentation
• I have updated the chart changelog with all the changes that come with this pull request according to changelog.
• Any new values are backwards compatible and/or have sensible default.
• I have signed off all my commits as required by DCO.
• My build is green (troubleshooting builds).

[yu-croco]

✏️ https://argo-cd.readthedocs.io/en/stable/operator-manual/applicationset/Template/#template-patch

[mkilchhofer]

LGTM

Rendered output

$ helm template . --values ci/applicationsets-values.yaml
---
# Source: argocd-apps/templates/applicationsets.yaml
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: applicationset
spec:
  generators:
    - git:
        directories:
        - path: guestbook
        - path: kustomize-*
        repoURL: https://github.com/argoproj/argocd-example-apps.git
        revision: HEAD
  ignoreApplicationDifferences:
    - jsonPointers:
      - /spec/syncPolicy
  syncPolicy:
    preserveResourcesOnDeletion: false
  template:
    metadata:
      name: '{{path.basename}}'
    spec:
      project: 'default'
      source:
        path: '{{path}}'
        repoURL: https://github.com/argoproj/argocd-example-apps.git
        targetRevision: HEAD
      destination:
        namespace: default
        server: https://kubernetes.default.svc
      syncPolicy:
        automated:
          prune: false
          selfHeal: false
      ignoreDifferences:
        - group: apps
          jsonPointers:
          - /spec/replicas
          kind: Deployment
      info:
        - name: url
          value: https://argoproj.github.io/
  templatePatch: |
    spec:
      source:
        helm:
          valueFiles:
          {{- range $valueFile := .valueFiles }}
            - {{ $valueFile }}
          {{- end }}
    {{- if .autoSync }}
      syncPolicy:
        automated:
          prune: {{ .prune }}
    {{- end }}
---
# Source: argocd-apps/templates/applicationsets.yaml
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: applicationset-list-generator
spec:
  generators:
    - list:
        elements:
        - cluster: engineering-dev
          url: https://kubernetes.default.svc
        template:
          metadata: {}
          spec:
            destination: {}
            project: '{{cluster}}'
            source:
              path: applicationset/examples/template-override/{{cluster}}-override
              repoURL: https://github.com/argoproj/argo-cd.git
              targetRevision: HEAD
  template:
    metadata:
      name: '{{cluster}}-guestbook'
    spec:
      project: '{{cluster}}'
      source:
        path: applicationset/examples/template-override/default
        repoURL: https://github.com/argoproj/argo-cd.git
        targetRevision: HEAD
      destination:
        namespace: guestbook
        server: '{{url}}'

[oscrx]

LGTM

[jwitko]

thank you!