chore: Add kustomization.yaml for server app RBAC (argoproj#15124)

This change adds a `kustomization.yaml` file for the example RBAC
role/rolebinding for argocd server applications.
This makes it easier to include them as resources in another `kustomization.yaml`.

Instead of including

```yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- https://raw.githubusercontent.com/argoproj/argo-cd/v2.8.0/examples/k8s-rbac/argocd-server-applications/argocd-server-rbac-clusterrole.yaml
- https://raw.githubusercontent.com/argoproj/argo-cd/v2.8.0/examples/k8s-rbac/argocd-server-applications/argocd-server-rbac-clusterrolebinding.yaml
```

the user can now instead include

```yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- github.com/argoproj/argo-cd/examples/k8s-rbac/argocd-server-applications?ref=v2.8.0
```

This change was performed by running:

```console
kustomize create
kustomize edit add resource argocd-server-rbac-clusterrole.yaml
kustomize edit add resource argocd-server-rbac-clusterrolebinding.yaml
```

Signed-off-by: Andreas Lindhé <[email protected]>
Signed-off-by: Alexy Mantha <[email protected]>

examples/k8s-rbac/argocd-server-applications/kustomization.yaml

@@ -0,0 +1,5 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- argocd-server-rbac-clusterrole.yaml
+- argocd-server-rbac-clusterrolebinding.yaml