src/vs/platform/theme/common/colorRegistry.ts/resolveColorValue
export function resolveColorValue(colorValue: ColorValue | null, theme: IColorTheme): Color | undefined {
	if (colorValue === null) {
		return undefined;
	} else if (typeof colorValue === 'string') {
		if (colorValue[0] === '#') {
			return Color.fromHex(colorValue);
		}
		return theme.getColor(colorValue);
	} else if (colorValue instanceof Color) {
		return colorValue;
	} else if (typeof colorValue === 'object') {
		return executeTransform(colorValue, theme);
	}
	return undefined;
}