src/vs/base/common/comparers.ts/compareFileExtensionsUpper
export function compareFileExtensionsUpper(one: string | null, other: string | null): number {
	one = one || '';
	other = other || '';
	const oneExtension = extractExtension(one);
	const otherExtension = extractExtension(other);
	const collatorNumeric = intlFileNameCollatorNumeric.value.collator;
	const collatorNumericCaseInsensitive = intlFileNameCollatorNumericCaseInsensitive.value.collator;

	return compareAndDisambiguateByLength(collatorNumericCaseInsensitive, oneExtension, otherExtension) ||
		compareCaseUpperFirst(one, other) ||
		compareAndDisambiguateByLength(collatorNumeric, one, other);
}