ENH: Make ExtensionDtype.numpy_dtype part of the interface?

[mroeschke]

pandas.ArrowDtype and nullable types define numpy_dtype to express the analogous NumPy type. Should ExtensionDtype.numpy_dtype be part of the interface as well, defaulting to np.dtype(object)?

[jbrockmendel]

What would it be used for?

[jorisvandenbossche]

Some related previous discussion: #22791

[mroeschke]

I think the motivations are covered in #22791, so I'll close this issue