Adds new transcend API spec for fetching policies with dynamic variables

[michaelfarrell76]

Working on some new endpoints that are included in the transcend consent manager UI API.

There are 2 new APIS that are being exposed:

1. transcend.setTranscendUiVariables - this allows for setting dynamic variables that can be used to template into the message contents displayed in the Transcend UI or when fetching policies
2. transcend.getTranscendPolicies returns the ID, title and translated content of a Transcend policy. these may be policies shown on the privacy center, or hidden policies distributed by our privacy center CDN. this content is templated with the same variables set by transcend.setTranscendUiVariables
3. transcend.getTranscendUiVariables returns the current set of global variables

        transcend
          .setTranscendUiVariables({
            labelName: 'Marshmalt Records',
          })
          .then(() => {
            transcend
              .getTranscendPolicies({
                policyTitles: ['Label Privacy Policy'],
                // variables: { labelName: 'Marshmalt Records' },
              })
              .then(([policy]) => {
                document.getElementById('policy-content').innerHTML =
                  policy.content;
              });
          });

[eligrey]

lgtm!