function isSubsetByComparator(comparator, arrA, arrB) {
	return arrA.every(a => arrB.some(b => comparator(a, b)));
}
Determines whether the first given array is a subset of the second given array.
@param {Function} comparator A function to compare two elements, should return `true` if they are equal.
@param {Array} arrA The array to compare from.
@param {Array} arrB The array to compare against.
@returns {boolean} `true` if the array `arrA` is a subset of the array `arrB`.