gh-143005: prevent incompatible __class__ reassignment for ctypes arrays

[VanshAgarwal24036]

This PR fixes a heap buffer overflow in ctypes arrays caused by assigning
class to an incompatible array type.

The change rejects class reassignment when the new array type differs
in length, size, or element type, preventing out-of-bounds memory access.
A regression test is included.

• Issue: Heap buffer overflow in ctypes array assignment via __class__ swap #143005

[VanshAgarwal24036]

@serhiy-storchaka
I’ve opened a PR fixing the ctypes array class reassignment issue discussed here.
CI is green now; no rush, just sharing in case you have time to take a look.

[serhiy-storchaka]

Thank you for your PR, @VanshAgarwal24036. I did not know what to do with this issue. It seems that adding check in tp_setattro is the way to go. But I suspect we need more tests -- each condition should be covered by alternate tests,