test pow() and bitwise shifts with scalars

[ev-br]

towards #299

[ev-br]

Ran 20_000 examples locally with jax.numpy, cupy, torch, numpy and array_api_strict.
The only issue is that
test_binary_with_scalars_real[pow] needs to be xfailed under CuPy 13.x, which does not fully implement NEP 50. The issue with pow is fixed in CuPy 14.0.0a1, so will be able to remove the xfail when 14.x becomes the minimum supported CuPy version. Until then, it's an xfail; which I'll add in a separate PR to array-api-compat.