Add Static Plan Hierarchy

Prior to this commit the plan_hierarchy would have to be added to the environment hiera.yaml in order to to hiera lookups from apply blocks in plans.

This change has no impact but to prevent having to add it later

Author: MartyEwings

hiera.yaml

@@ -10,3 +10,7 @@ hierarchy:
     paths:
       - "nodes/%{trusted.certname}.yaml"
       - "common.yaml"
+plan_hierarchy:
+  - name: "Static data"
+    data_hash: yaml_data
+    path: "static.yaml"