emoji_eventsDeep equality

Write deepEqual(a, b) that compares two values by content, the way test libraries do.

• Primitives compare with ===, except that NaN equals NaN.
• Arrays are equal when they have the same length and equal items in order.
• Plain objects are equal when they have the same keys and equal values (key order does not matter).
• Dates are equal when they hold the same time.

Acceptance criteria

• deepEqual([1, 2], { 0: 1, 1: 2 }) is false (an array is not an object).
• The tests at the bottom print All tests passed.