message: Re-add messages field in policy table json
  consumer_friendly_messages.messages was being omitted from the policy table json rather than just the snapshot, this reintroduces this field (this field is still cleared out when generating the snapshot in `CheckSnapshotInitialization`)
diff: @@ -1357,8 +1357,7 @@ ConsumerFriendlyMessages::ConsumerFriendlyMessages(const Json::Value* value__)
  Json::Value ConsumerFriendlyMessages::ToJsonValue() const {
  Json::Value result__(Json::objectValue);
  impl::WriteJsonField("version", version, &result__);
  - // According to requirements, it is not necessary to provide this to PTS
  - // impl::WriteJsonField("messages", messages, &result__);
  + impl::WriteJsonField("messages", messages, &result__);
  return result__;
  }
  