feat: Custom Healthcare API endpoint (#1367)

* Add ability to configure Google Cloud Healthcare API endpoint.

* Fixed bug in script.

* Fixed PR remark.

* Set Healthcare API endpoint in proper place.

platform/viewer/public/config/google.js

@@ -2,6 +2,7 @@ window.config = {
   routerBasename: '/',
   whiteLabelling: {},
   enableGoogleCloudAdapter: true,
+  healthcareApiEndpoint: 'https://healthcare.googleapis.com/v1beta1',
   servers: {
     // This is an array, but we'll only use the first entry for now
     dicomWeb: [],