Gtk::Entry: Remove property_activate()
Gtk::Entry: Remove property_activate()

and add property_enable_emoji_completion().
GtkEntry:activate shall not be used in application programs in gtk4.
See https://gitlab.gnome.org/GNOME/gtk/commit/78a9b5d1edfb6da871cb73cf493f871de3fb6769

GNOME/gtkmm,GNOME/gtkmm,GNOME/gtkmm,GNOME/gtkmm