Disabled DragValue still resets focus when using tab-navigation

[KonaeAkira]

Related issue: #5359

It seems like #5370 doesn't fully fix the issue, because a disabled DragValue will still eat the focus, resulting in nothing being focused when using TAB to navigate.

I've made the following test case to verify it:

// crates/egui_kittest/tests/regression_tests.rs

#[test]
pub fn focus_should_skip_over_disabled_drag_values() {
    let mut value_1: u16 = 1;
    let mut value_2: u16 = 2;
    let mut value_3: u16 = 3;

    let mut harness = Harness::new_ui(|ui| {
        ui.add(DragValue::new(&mut value_1));
        ui.add_enabled(false, DragValue::new(&mut value_2));
        ui.add(DragValue::new(&mut value_3));
    });

    harness.press_key(egui::Key::Tab);
    harness.run();

    let drag_value_1 = harness.get_by(|node| node.numeric_value() == Some(1.0));
    assert!(drag_value_1.is_focused());

    harness.press_key(egui::Key::Tab);
    harness.run();

    let drag_value_3 = harness.get_by(|node| node.numeric_value() == Some(3.0));
    assert!(drag_value_3.is_focused()); // assertion failed: drag_value_3.is_focused()
}