Apps with missing icons in activity switcher

Because of how GTK3 handles app-ids, some applications have their icons in the activity switcher missing. Those that we forked should get fixed in the package, while for others it may not be a bad idea to have some compatibility mapping in phosh at some point (in addition to getting them fixed upstream).

Here's the list of packages where I noticed missing icons:

• gnome-2048
• gnome-authenticator
• cawbird
• gnome-disk-utility
• eog
• lightsoff
• iagno
• gnome-sound-recorder
• stream (lacks window title too)
• gedit
• tootle
• pinhole (lacks window title too)
• dconf-editor
• seahorse
• gnome-power-manager
• sysprof