extensions/git/src/util.ts/isDescendant
export function isDescendant(parent: string, descendant: string): boolean {
	if (parent === descendant) {
		return true;
	}

	if (parent.charAt(parent.length - 1) !== sep) {
		parent += sep;
	}

	// Windows is case insensitive
	if (isWindowsPath(parent)) {
		parent = parent.toLowerCase();
		descendant = descendant.toLowerCase();
	}

	return descendant.startsWith(parent);
}