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/progress-bar.md

@@ -45,7 +45,7 @@ Starting with a working application from the
 [Quick Start Guide](quick-start.md), add the following lines to the
 `main.js` file:
 
-```javascript
+```javascript fiddle='docs/fiddles/features/progress-bar'
 const { BrowserWindow } = require('electron')
 const win = new BrowserWindow()