Rename .js.es6 to .js in the admin application

app/assets/javascripts/admin/controllers/admin-email-advanced-test.js

@@ -0,0 +1,31 @@
+import Controller from "@ember/controller";
+import { ajax } from "discourse/lib/ajax";
+import { popupAjaxError } from "discourse/lib/ajax-error";
+
+export default Controller.extend({
+  email: null,
+  text: null,
+  elided: null,
+  format: null,
+  loading: null,
+
+  actions: {
+    run() {
+      this.set("loading", true);
+
+      ajax("/admin/email/advanced-test", {
+        type: "POST",
+        data: { email: this.email }
+      })
+        .then(data => {
+          this.setProperties({
+            text: data.text,
+            elided: data.elided,
+            format: data.format
+          });
+        })
+        .catch(popupAjaxError)
+        .finally(() => this.set("loading", false));
+    }
+  }
+});