gtk/imcontextwayland: Unset focus when unsetting widget

In destruction paths of a focused entry, the IM context might first
end up detached from its widget, then destroyed. This currently prevents
the IM context from detaching itself from the GtkIMContextWaylandGlobal.

Make it do so when unsetting the client widget, so the IM context gets
properly unfocused before destruction.

Fixes: https://gitlab.gnome.org/GNOME/gtk/-/issues/3176

gtk/gtkimcontextwayland.c

@@ -546,6 +546,7 @@ gtk_im_context_wayland_set_client_widget (GtkIMContext *context,
 
   if (context_wayland->widget)
     {
+      gtk_im_context_wayland_focus_out (context);
       gtk_widget_remove_controller (context_wayland->widget, GTK_EVENT_CONTROLLER (context_wayland->gesture));
       context_wayland->gesture = NULL;
     }