Summary:
I wanted to debug why an application didn't start, this helped me see that it
was found and in which phase.
It's not installed for now.

Test Plan:
```
$ ./bin/plasma-autostart
phase: 0
- org.kde.plasmashell /home/apol/devel/kde5/etc/xdg/autostart/org.kde.plasmashell.desktop
- polkit-kde-authentication-agent-1 /home/apol/devel/kde5/etc/xdg/autostart/polkit-kde-authentication-agent-1.desktop
- xembedsniproxy /home/apol/devel/kde5/etc/xdg/autostart/xembedsniproxy.desktop

phase: 1
- gmenudbusmenuproxy /home/apol/devel/kde5/etc/xdg/autostart/gmenudbusmenuproxy.desktop
- pulseaudio /etc/xdg/autostart/pulseaudio.desktop
- org.kde.discover.notifier /home/apol/devel/kde5/etc/xdg/autostart/org.kde.discover.notifier.desktop
- org.kde.kdeconnect.daemon /home/apol/devel/kde5/etc/xdg/autostart/org.kde.kdeconnect.daemon.desktop

phase: 2
- geoclue-demo-agent /etc/xdg/autostart/geoclue-demo-agent.desktop
- gnome-shell-overrides-migration /etc/xdg/...