Improve inferring the "final" static type when calling static methods inside a different class

[someniatko]

fixes #8200

After some insane debugging and trying to wrap my head around it, I found the reason it behaves improperly.

When calling a static method of some class, there are two possibilities:

1. in the static method itself there might be something like @return Collection<static>, that means static is defined by the static method which we are calling.
2. this static method is parameterized with a template like @return Collection<T>, but the class which CALLS it can have something like @return Collection<static>. So static is defined by the CALLING code, not the CALLED. In this case, Psalm behaved incorrectly, because it always assumed only the 1st case.

I have to move the test case somewhere (for now it's a separate class), please give a hint.

[AndrolGenhald]

I have to move the test case somewhere (for now it's a separate class), please give a hint.

It looks like ClassTest has some other static stuff like allowFinalReturnerForStatic and intersectWithStatic, so I'd just put it there. Test organization isn't the best...

[someniatko]

meh, when moving test cases I added them to "invalid code" section instead of "valid code"

[AndrolGenhald]

Please indent the test code one level past the <?php tag to match the other tests. LGTM after that's done.

[AndrolGenhald]

Thanks!