batch-rename-dialog: Don't use GtkContainer::add()

Instead of creating GtkListBoxRows directly, we can just create their
child widget and use GtkListBox::insert() method directly.

This prepares for GTK4, where GtkContainer is gone.
2 jobs for wip/antoniof/gtk4-preparation-batch-rename-dialog in 5 minutes and 57 seconds (queued for 6 seconds)