Added stripe load method

no issue

- Load Stripe script if not already loaded on page
- Many members.js features rely on Stripe script to be loaded on the page to allow checkout/billing updates etc.

ghost/portal/src/index.js

@@ -11,6 +11,20 @@ function addRootDiv() {
     document.body.appendChild(elem);
 }
 
+function loadStripe() {
+    // We don't want to load Stripe again if already loaded
+    if (!window.Stripe) {
+        // Get the first script element on the page
+        const ref = document.getElementsByTagName('script')[0];
+        // Create a new script element
+        const script = document.createElement('script');
+        // Set the script element `src`
+        script.src = 'https://js.stripe.com/v3/';
+        // Inject the script into the DOM
+        ref.parentNode.insertBefore(script, ref);
+    }
+}
+
 function handleTokenUrl() {
     const url = new URL(window.location);
     if (url.searchParams.get('token')) {