Reintroduce contentLoading loginc for legacy view

aleksis/core/assets/components/LegacyBaseTemplate.vue

@@ -75,8 +75,15 @@ export default {
     // Subscribe to message channel to receive height from iframe
     window.addEventListener("message", this.receiveMessage);
   },
+  watch: {
+    $route() {
+      // Show loading animation once route changes
+      this.$root.contentLoading = true;
+    },
+  },
   beforeDestroy() {
     window.removeEventListener("message", this.receiveMessage);
+    this.$root.contentLoading = false;
   },
   name: "LegacyBaseTemplate",
 };