rec: Manage the applied policy and tags from pre/post resolve hooks

rec: Manage the applied policy and tags from pre/post resolve hooks

This adds a `appliedPolicy` string member to the dq object, along
with new methods:
 * `addPolicyTag(string)`
 * `setPolicyTags(table of strings)`
 * `getPolicyTags()`
A new repeated (ie, {0,n}) `tags` is added to our protobuf responses.