src/vs/base/common/arrays.ts/commonPrefixLength
export function commonPrefixLength<T>(one: ReadonlyArray<T>, other: ReadonlyArray<T>, equals: (a: T, b: T) => boolean = (a, b) => a === b): number {
	let result = 0;

	for (let i = 0, len = Math.min(one.length, other.length); i < len && equals(one[i], other[i]); i++) {
		result++;
	}

	return result;
}