Apply transformation to individual shape

[musjj]

It would be nice if we can apply transformations to individual shapes, rather than the entire mesh.

This way we can combine multiple shapes with different transformations, like this:

let extents = Vec2::new(10., 5.);
                                                        
let rectangle_1 = shapes::Rectangle {
    extents,
    ..default()
};
let quat = Quat::from_rotation_z(-45_f32.to_radians());
let transform = Transform::from_rotation(quat);
rectangle_1.transform(transform);
                                                        
let rectangle_2 = shapes::Rectangle {
    extents,
    ..default()
};
let quat = Quat::from_rotation_z(45_f32.to_radians());
let transform = Transform::from_rotation(quat);
rectangle_2.transform(transform);
                                                        
let shape = ShapeBundle {
    path: GeometryBuilder::new()
        .add(&rectangle_1)
        .add(&rectangle_2)
        .build(),
    ..default()
};