Replace ui.ctx().foo with ui.foo in a few places (#7774)

Internal code cleanup after
* https://github.com/emilk/egui/pull/7770

crates/egui_demo_lib/src/demo/modals.rs

@@ -149,7 +149,7 @@ impl crate::View for Modals {
                     *user_modal_open = false;
                 } else {
                     *save_progress = Some(progress + 0.003);
-                    ui.ctx().request_repaint();
+                    ui.request_repaint();
                 }
             });
         }