feat: add Arr::after() to retrieve the value after the given value

[gulfaraz-arshad]

What this PR does

Adds a new static Arr::after() method that retrieves the value
after the given value in an array. Wraps around to the first
element if the given value is the last one.

Usage

Arr::after(['a', 'b', 'c'], 'a'); // 'b'
Arr::after(['a', 'b', 'c'], 'c'); // wraps → 'a'
Arr::after(['a', 'b', 'c'], 'z'); // not found → null
Arr::after(['x' => 'a', 'y' => 'b'], 'a'); // 'b'

Why

This is a common pattern when building carousels, step wizards,
rotating queues, or any sequential navigation logic. The name
after() is consistent with how Laravel uses it in migrations
(->after()). Having it in Arr keeps it consistent with
helpers like Arr::first() and Arr::last().

[shaedrich]

Your target branch doesn't seem to be the same as the branch you created your feature branch from

[shaedrich]

Arr::after(['a', 'b', 'c'], 'c'); // wraps → 'a'
Arr::after(['a', 'b', 'c'], 'z'); // not found → null
Arr::after(['x' => 'a', 'y' => 'b'], 'a'); // 'b'

Honestly, it makes sense for carousels, but not so much for the general use. I'd introduce a flag, which would affect it like this:

// without flag
Arr::after(['a', 'b', 'c'], 'c'); // null (`RangeException` would work but would probably be annoying)
Arr::after(['a', 'b', 'c'], 'z'); // not found → throws
Arr::after(['x' => 'a', 'y' => 'b'], 'x'); // 'b' → returns value

// with flag
Arr::after(['a', 'b', 'c'], 'c', wrap: true); // wraps → 'a'
Arr::after(['a', 'b', 'c'], 'z', wrap: true); // not found → 'a'
Arr::after(['x' => 'a', 'y' => 'b'], 'x'); // 'b'

What do you think?

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!