docs: Added Native User Interface -> Open path in file manager Fiddle example (#20589)

* docs: Added Native User Interface -> Open path in file manager Fiddle example from electron-api-demos

* removed classname from button

docs/fiddles/native-ui/external-links-file-manager/path-in-file-manager/main.js

@@ -0,0 +1,25 @@
+const { app, BrowserWindow } = require('electron')
+
+let mainWindow = null
+
+function createWindow () {
+  const windowOptions = {
+    width: 600,
+    height: 400,
+    title: 'Open Path in File Manager',
+    webPreferences: {
+      nodeIntegration: true
+    }
+  }
+
+  mainWindow = new BrowserWindow(windowOptions)
+  mainWindow.loadFile('index.html')
+
+  mainWindow.on('closed', () => {
+    mainWindow = null
+  })
+}
+
+app.on('ready', () => {
+  createWindow()
+})