Added more precise return types on Zend_Controller_Request_Http

[staabm]

when invoked without parameterts like $post = $this->getRequest()->getPost(); with this PR we can assume we get an array.

this simplifies handling on the caller-side as we no longer get mixed.

the precise return type is inspired by phpstan-src

[staabm]

even if these annotations are prefixed with phpstan- they also work for psalm

[boenrobot]

Just an opinion as a user...

If you're going to go all in on more accurate typing, maybe further expand the mixed into what it is... And on a related note, does PHP and ZF do casting to a number, or is it always a string? I'm pretty sure there's no way to get a boolean from a $_GET, $_POST or $_COOKIE, but I'm not so sure for the other scalar types. Oh, and maybe to define the return type in terms of the default value?

So something like this perhaps

@template T
@phpstan-param T $default
@phpstan-return ($key is null ? array<string, string|int|double|array> : string|int|double|array|T)