Create auto queries

[DarkRewar]

Allow ui elements to be automatically retrieved at awake/start or anywhere at anytime by using attributes.
Example:

[View("MyViewId")]
public class MyView : MonoBehaviour
{
    [Query("MainModal")]
    public VisualElement MainModal;

    [Query<Button>()]
    public List<Button> Buttons;

    [Query(".unity-label")]
    public Label[] Labels;

    [Query<ScrollView>("TimelineScroll")]
    private ScrollView _scrollView;

    public void OnEnable() => View.ExecuteQueries(this);
}

[DarkRewar]

Generic attribute [Query<Button>()] is not available in Unity 6 (using C#9), must waiting for C#11... later...

[DarkRewar]

Using attributes will require to use reflection, which is too heavy...