Patch 2/2 (other patch is D12040 for plasma-workspace)
Depends on D12040
FEATURE: 386621
Not sure I should be depending on the "image" C++ plugin here.
Screenshot:
{F5800267}
Which opens this GHNS window from Patch 1:
{F5800268}
### TODO:
* [x] Move C++ plugin to `components/shellprivate/wallpaperplugin` ? I probably need to move the new GHNS code to `components/shellprivate/wallpaperplugin` since "desktoppackage" has the widgetexplorer C++ plugins there. I figured I'd put up a working patch first.
* [ ] Update `wallpaperComboBox` and `configDialog.wallpaperConfigModel` so we don't have to close and reopen the "Configure Desktop" window for the plugin to show up in the dropdown.