jobs-systemd: Set DESKTOP_FILE_HINT environment variable
Lomiri checks for the supplied desktop file hint through these 2 methods:
- Check the argv of the app
- Fall back to checking the hint through it's environ
- Disallow connection if neither could be read
Click apps, if they do, they usually override the desktop_file_hint in argv, but apps outside of the Open Store are left with no way to match icons & allow access to spawn windows altogether. Hence enable DESKTOP_FILE_HINT as an environment variable in any case when spawned using systemd.
This way apps from other stores are able to connect properly to the shell.