feat(argo-workflows): add imagePullSecret for workflow sa (#2226)

Signed-off-by: Fuochi <ffuochi@hotmail.com>

charts/argo-workflows/values.yaml

@@ -54,6 +54,8 @@ workflow:
     annotations: {}
     # -- Service account which is used to run workflows
     name: "argo-workflow"
+    # -- Secrets with credentials to pull images from a private registry. Same format as `.Values.images.pullSecrets`
+    pullSecrets: []
   rbac:
     # -- Adds Role and RoleBinding for the above specified service account to be able to run workflows.
     # A Role and Rolebinding pair is also created for each namespace in controller.workflowNamespaces (see below)