add the app url input on the first setup page

app/javascript/elements/set_origin_url.js

@@ -0,0 +1,7 @@
+export default class extends HTMLElement {
+  connectedCallback () {
+    if (this.dataset.inputId) {
+      document.getElementById(this.dataset.inputId).value = document.location.origin
+    }
+  }
+}