refactor: implement concrete Delivery responsibility dispositions

tests/contract.json

@@ -0,0 +1,9 @@
+[
+  "Stop when the policy cannot be loaded",
+  "presence only",
+  "never inspect, hash or measure",
+  "Reject unexpected redirects",
+  "not authority to administer accounts",
+  "separately verified delegation",
+  "Never persist"
+]