Fix array_* function signatures

[othercorey]

array_replace historically could return null on a type error, but that didn't seem like a worthwhile edge case to add. It should always return an array and since 8.0 will always return an array.

[othercorey]

Looks like a few other functions were changed to allow optional arguments, but I have to figure out when they changed since it's not documented.

[AndrolGenhald]

but I have to figure out when they changed since it's not documented.

You can go ahead an open an issue for https://github.com/php/doc-en for that.

[othercorey]

You can go ahead an open an issue for https://github.com/php/doc-en for that.

I submitted patches for missing documentation.

Looks like array_replace $replacements was always optional so that should be the last fix.

[orklah]

Thanks for your work on that! That's great!