docs: added fiddle support for code samples (#26501)

* docs: added fiddle support for code samples in quick start guide and features

* docs: removed excessive fiddle links for not final steps

* docs: added eof newlines to fiddle examples

* docs: reworked fiddle examples to be more self-sufficient

* docs: reworked fiddle examples according to mentions

* docs: changed http to https in the offscreen rendering fiddle

* docs: fix recent documents fiddle to be more consistent

docs/fiddles/features/notifications/renderer/renderer.js

@@ -0,0 +1,7 @@
+const myNotification = new Notification('Title', {
+  body: 'Notification from the Renderer process'
+})
+
+myNotification.onclick = () => {
+  console.log('Notification clicked')
+}