ui: Rename UI files to .ui (instead of .xml)
When using GtkApplication, Gtk automatically searches for the menus of
the application at "org/example/app/gtk/menus.ui".
Currently we don't have a "menus.ui", but try to see this commit is a
first step in order to use app-menu.
For now, let's standardize that all our UI files will have the ".ui"
extension instead of the ".xml" one.
Signed-off-by: Fabiano FidĂȘncio <fidencio@redhat.com>
Acked-by: Jonathon Jongsma <jjongsma@redhat.com>