Add QR code icon, button, modal for invites

Using https://excid3.github.io/tailwindcss-stimulus-components/

app/javascript/controllers/application.js

@@ -1,7 +1,10 @@
 import { Application } from "@hotwired/stimulus"
+import { Modal } from "tailwindcss-stimulus-components"
 
 const application = Application.start()
 
+application.register('modal', Modal)
+
 // Configure Stimulus development experience
 application.debug = false
 window.Stimulus   = application