Description of the new feature/enhancement

When you install a distro for WSL, it should automatically launch with the default desktop wallpaper as the background to provide users with a familiar experience.

This is just a visual aesthetic that many people would appreciate. It's the small things that can make such a huge difference.

Proposed technical implementation details (optional)

Add the background images to defaults.json for each distro profile. We should start with the ones in the Store like Ubuntu but we should accept community contributions for other distros that are custom imported as well such as Clear Linux.

I'd like to see background automatically set to the image stored locally on the computer to each distro profile so if I open a distro, I'll see that background by default. Users can still override it in settings.json.