Fixes #28070

In the example presented in #28070 there's an unnecessary copy made by calling __array__ with copy=True:

import numpy as np

class MyThing(object):
    def __array__(self, dtype=None, copy=None):
        print(f"MyThing.__array__(dtype={dtype}, copy={copy})")
        return np.ones((5, 5))

u = np.zeros((5, 5))
v = MyThing()

u[...] = v

I think we can switch from "always copy" to "copy if needed" for the input shape&dtype discovery in the PyArray_CopyObject function.
I want to stress that the src to dest copy is done anyway (AFAIU indexed assignment can't return a view) as PyArray_CopyObject calls PyArray_AssignArray(dest, src, ...) which iterates over elements and copies them to dest.