tui: add group-forward-mask property to bridge page

The validation on allowed bits is done when the user saves the
connection.

https://bugzilla.redhat.com/show_bug.cgi?id=1358615

clients/tui/nmt-page-bridge.c

@@ -147,6 +147,12 @@ nmt_page_bridge_constructed (GObject *object)
 	label = nmt_newt_label_new (_("seconds"));
 	nmt_editor_grid_append (grid, _("Max age"), widget, label);
 
+	widget = nmt_newt_entry_numeric_new (10, 0, 65535);
+	g_object_bind_property (s_bridge, NM_SETTING_BRIDGE_GROUP_FORWARD_MASK,
+	                        widget, "text",
+	                        G_BINDING_BIDIRECTIONAL | G_BINDING_SYNC_CREATE);
+	nmt_editor_grid_append (grid, _("Group forward mask"), widget, NULL);
+
 	nmt_editor_page_add_section (NMT_EDITOR_PAGE (bridge), section);
 
 	G_OBJECT_CLASS (nmt_page_bridge_parent_class)->constructed (object);