Allow Graphics.DrawText to vertically align unwrapped text

Allow the five-argument Graphics.DrawText() overload to vertically align text within its boundingHeight when wrapWidth is zero or negative. Non-positive widths should continue to draw a single unwrapped line while VerticalTextAlignment.Middle and .Bottom position that line within the requested height. This avoids a separate text-measurement call when callers need vertically aligned text without wrapping.