[5.4] Add $num optional parameter to Arr::random()

[vlakoff]

Follow-up to #19741.

There is a bit of room for improvement. Mainly, the function would fail if requesting more items than available. This can be dealt with later, here I do this PR to quickly alter the method signature while it is fresh.

ping @calebporzio

[vlakoff]

array_random($array, 1) behaves as array_random($array), i.e. it directly returns the random item.

Is it ok, or should it be changed to behave as array_random($array, N), i.e. returning an array of one item?

[vlakoff]

Indeed that's what Collection::random() does. random() directly returns the item, random(1) returns an array of one item. Do you agree Arr::random() should do the same?

[calebporzio]

I think so, it more closely matches array_rand as well - I will submit a PR as soon as I get the chance.

[vlakoff]

I'm already on it :) Also, refs #16865.

[calebporzio]

Cool 👍