brasero-project-type-chooser: fix icons on buttons for 'Recent projects'

The call to gtk_recent_info_get_icon() causes a segfault as a member of the
GtkIconSize enum is no longer a valid size parameter for this function
following a recent round of deprecations.

Instead use gtk_recent_info_get_gicon () and create the GtkImage from the
GIcon with the desired size.