Retain hue when contrast shifts luminance in other direction

[Tyriar]

Currently if contrast can't be met going the natural direction, we switch and go the other direction but this is done by using the background as the foreground:

Code:

xterm.js/src/common/Color.ts

Lines 197 to 201 in 384cd9d

	if (resultARatio < ratio) {
	const resultB = increaseLuminance(bgRgba, bgRgba, ratio);
	const resultBRatio = contrastRatio(bgL, rgb.relativeLuminance(resultB >> 8));
	return resultARatio > resultBRatio ? resultA : resultB;
	}

xterm.js/src/common/Color.ts

Lines 206 to 210 in 384cd9d

	if (resultARatio < ratio) {
	const resultB = reduceLuminance(bgRgba, bgRgba, ratio);
	const resultBRatio = contrastRatio(bgL, rgb.relativeLuminance(resultB >> 8));
	return resultARatio > resultBRatio ? resultA : resultB;
	}

More ideal would be to retain the hue of the original color, so we would continue to use fgRgba here which should make the folder above still have a blue hue and the branch still have a yellow hue.