PHP 8.4: Implicitly nullable parameter declarations deprecated

[marcing]

PHP 8.4: Implicitly nullable parameter declarations deprecated

https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated

Fixes error:
Implicitly marking parameter ? as nullable is deprecated, the explicit nullable type must be used instead

Fix using Zf1s\Compat\Types

[dmnc]

This is a tricky one. If I understand correctly, we can not make 8.4 happy whilst supporting less than 7.1.

This seems to prevent a conflict between keeping ZF1 usable on new PHP versions with this package and fixing vulnerabilities with it.

The approach taken here makes me a little nervous but it does seem to perform what we want:

• Compatible with all PHP versions
• Doesn't break child classes that have types on these methods
• Has thorough docblocks so editors remain able to understand the expected type.

It does introduce a surprising pattern though. Is that preferable to making future version >=7.1?

[marcing]

@dmnc No actually in the end I managed to make it work on all versions 5.6-8.4. I had to introduce a helper function though, because there is no syntax that would work in both 5.6 and 8.4.