Set prgname to application ID

Using the application ID ensures that Wayland compositors could match the window with the application and show the appropriate icon for them.

Also set the icon for the addressbook.

References:

• https://honk.sigxcpu.org/con/GTK__and_the_application_id.html
• https://docs.gtk.org/gtk4/migrating-3to4.html#set-a-proper-application-id