function textElRhombWidth(textEl) {
	const farthestPoint = svgTxtFarthestPoint(textEl);
	return 2 * (Math.abs(farthestPoint.x) + Math.abs(farthestPoint.y));
}
calc width of the square rhomb that cover all tspan in {textEl}
origin is in the center of the rhomb
@param {SVGTextElement} textEl