BUG: don't assume strides are a multiple of itemsize in stringdtype casts (#32273) - #32292

>>> rec = np.zeros(3, dtype=[("c", "c16"), ("f", "f8")])
... rec["c"] = [1 + 1j, 2 + 2j, 3 + 3j]
... rec["f"] = [10.0, 20.0, 30.0]
...
>>> rec["c"].astype("T")
array(['(1+1j)', '(10+2j)', '(2+20j)'], dtype=StringDType())
>>> rec["c"]
array([1.+1.j, 2.+2.j, 3.+3.j])
>>> np.__version__
'2.5.2'