use promisedRequest for theme resource fetching

src/api/helpers.js

@@ -71,6 +71,7 @@ export const promisedRequest = async ({
   url,
   payload,
   formData,
+  cache,
   credentials,
   headers = {},
 }) => {
@@ -87,6 +88,10 @@ export const promisedRequest = async ({
     options.headers['Content-Type'] = 'application/json'
   }
 
+  if (cache) {
+    options.cache = cache
+  }
+
   if (formData || payload) {
     options.body = formData || JSON.stringify(payload)
   }