Decouple login modal opening from Angular

app/webpacker/controllers/login_modal_controller.js

@@ -0,0 +1,8 @@
+import { Controller } from "stimulus"
+
+export default class extends Controller {
+  call(event) {
+    event.preventDefault()
+    window.dispatchEvent(new Event("login:modal:open"))
+  }
+}