Allow setting container entrypoint

roles/container/meta/argument_specs.yaml

@@ -13,6 +13,11 @@ argument_specs:
         required: false
         default: []
         elements: str
+      container_entrypoint:
+        description: Entrypoint to use for the continaer
+        type: str
+        required: false
+        default: ""
       container_user:
         description: The UID to run as inside the container
         type: str