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/tutorial/notifications.md

@@ -28,7 +28,7 @@ Assuming you have a working Electron application from the
 
 and add the `renderer.js` file:
 
-```js
+```javascript fiddle='docs/fiddles/features/notifications/renderer'
 const myNotification = new Notification('Title', {
   body: 'Notification from the Renderer process'
 })
@@ -52,7 +52,7 @@ message that was generated after triggering the `onclick` event:
 Starting with a working application from the
 [Quick Start Guide](quick-start.md), update the `main.js` file with the following lines:
 
-```js
+```javascript fiddle='docs/fiddles/features/notifications/main'
 const { Notification } = require('electron')
 
 function showNotification () {