fix(gtk): confirm tab close on close_tab action (#5166)

#4033 introduced a `ctrl-shift-w` binding to close a tab, but it doesn't
respect the `confirm-close-surface` option. Now `ctrl-shift-w` will ask
for confirmation exactly the same as clicking the close button with the
mouse.

src/apprt/gtk/App.zig

@@ -579,7 +579,7 @@ fn closeTab(_: *App, target: apprt.Target) !void {
                 return;
             };
 
-            tab.window.closeTab(tab);
+            tab.closeWithConfirmation();
         },
     }
 }