os-database: Add guess_os_from_install_media
os-database: Add guess_os_from_install_media

A new method to guess media. Unlike guess_os_from_install_media_path,
this takes Osinfo.Media as input.

https://bugzilla.gnome.org/show_bug.cgi?id=694141

vbenes/gnome-boxes,vbenes/gnome-boxes