Add multiple preview URL whitelist entries

If you only have a single preview hostname and URL, it should be fully sufficient to set `studio.previewUrlPrefix` to that URL. Due to the CoreMedia issue CMS-21564, the Studio does not correctly handle the case where only `studio.previewUrlPrefix` is set, or `studio.preview-url-whitelist` has only a single entry. This results in error messages in the browser console similar to `Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('https://preview.127.0.0.1.nip.io') does not match the recipient window's origin ('https://studio.127.0.0.1.nip.io').`

Add the preview URL twice to `studio.preview-url-whitelist` to work around this.

src/main/java/com/tsystemsmms/cmcc/cmccoperator/components/corba/StudioServerComponent.java

@@ -92,6 +92,10 @@ public Map<String, String> getSpringBootProperties() {
 
         properties.putAll(getSiteMappingProperties());
         properties.put("studio.previewUrlPrefix", "https://" + getTargetState().getPreviewHostname());
+        // add the Studio URL twice time to work around CoreMedia bug CMS-21564. Normally, it should be sufficient
+        // to only have previewUrlPrefix set.
+        properties.put("studio.preview-url-whitelist[0]", "https://" + getTargetState().getPreviewHostname());
+        properties.put("studio.preview-url-whitelist[1]", "https://" + getTargetState().getPreviewHostname());
         properties.put("themeImporter.apiKeyStore.basePath", "/var/tmp/themeimporter");
 
         return properties;