Plumb through ImagePullSecrets to agent pod

Right now in the YTT templates we assume that the agent pods are gonna use
the same image as the main Pinniped deployment, so we can use the same logic
for the image pull secrets.

Signed-off-by: Andrew Keesler <akeesler@vmware.com>

deploy/deployment.yaml

@@ -45,6 +45,10 @@ data:
       (@ else: @)
       image: (@= data.values.image_repo + ":" + data.values.image_tag @)
       (@ end @)
+      (@ if data.values.image_pull_dockerconfigjson: @)
+      imagePullSecrets:
+        - image-pull-secret
+      (@ end @)
 ---
 #@ if data.values.image_pull_dockerconfigjson and data.values.image_pull_dockerconfigjson != "":
 apiVersion: v1