Electron - missing icons folder in build

[hawkeye64]

Describe the bug
When quasar build -m electron is issued, the src-electron/icons folder is not copied to the dist/electron/unpackaged folder and therefore will not be packaged into the final electron build.

Codepen/jsFiddle/Codesandbox (required)
Fork a Codepen (https://codepen.quasar.dev) or a jsFiddle (https://jsfiddle.quasar.dev) or a Codesandbox (https://codesandbox.quasar.dev) and hit save then copy-paste link here.

To Reproduce
Steps to reproduce the behavior:

1. run quasar build -m electron
2. go to the dist/electron/unpackaged folder
3. you will see it's missing the icons folder

Expected behavior
You'd expect the icons folder to be copied over

Screenshots

I have verified this for both Linux and Windows, but have not for Mac (but, assume it's the same)

Platform (please complete the following information):
Quasar Version:
@quasar/app Version:
Build mode........ electron
Pkg quasar........ v2.1.9
Pkg @quasar/app... v3.1.5

Quasar mode:

• SPA
• SSR
• PWA
• Electron
• Cordova
• Capacitor
• BEX

Tested on:

• SPA
• SSR
• PWA
• Electron
• Cordova
• Capacitor
• BEX

OS: windows 11/ubuntu 20.04.3
Node: 14.18.1
NPM: 6.14.15
Yarn: 1.22.15
Browsers:
iOS:
Android:
Electron:
"electron": "^15.3.0",
"electron-builder": "^22.4.0",
"electron-packager": "^15.2.0",

Additional context
I tried to find the code in @quasar/app that should do the copying but have not located it yet. I did set a breakpoint in vs code to stop the build. I manually copied the icons folder to unpackaged. I then let the build continue. When running the output on Ubuntu, the icon now shows up for the running app. On windows, the executable and setup both have embedded icons, and running the app shows the icon on the dock bar.

Also, for the icons to work, I added the following code in electron-main.js (note: this also works for dev):

const iconPath = path.resolve(__dirname, 'icons',
  os.platform === 'win32' ? 'icon.ico'
    : os.platform === 'darwin' ? 'icon.icns'
      : 'linux-512x512.png'
)

function createWindow () {
  /**
   * Initial window options
   */
  mainWindow = new BrowserWindow({
    icon: iconPath, // <-- here
    width: 1000,
    height: 600,
    useContentSize: true,
    webPreferences: {
      contextIsolation: true,
      // More info: /quasar-cli/developing-electron-apps/electron-preload-script
      preload: path.resolve(__dirname, process.env.QUASAR_ELECTRON_PRELOAD)
    }
  })

If I can figure this out, I will create a PR.