Add scaling support for ImageButton

[charlottetowell]

Adds new opt param scale for use in scaling an image. Currently only supports single scale factor for x and y.

Scales the image visually + updates the button hitbox as per scaled size.

Example use:

local button= {
    x = windowWidth,
    y = windowHeight,
    image = assets.button,
    hoveredImage = assets.buttonHover,
    scale = someScaleValue
}

function menuState:update(dt)
    if suit.ImageButton(button.image, {hovered=button.hoveredImage, scale=button.scale}, button.x, button.y).hit then
            print("Button clicked!")
    end
end