Enable array destructuring of Size::class with width & height

[olivervogel]

Describe the feature you'd like

Destructure a Size::class and be able to get width & height.

[$width, $height] = $image->size(); // (int) $width, (int) $height

Is your feature request related to a problem? Please describe.

Currently, a Size::class can be destructured, but you end up with individual points because the class is extended from Polygon::class. It would be better if only the width and height were destructured for this class like described above.

// width & height are both Intervention\Image\Geometry\Point first two points of the four rectangle points
[$width, $height] = $image->size();