Restore support for Numpy sparsely packed arrays

[lydia-duncan]

With array views implemented in Chapel, we lost the ability to send numpy arrays that are not densely packed to a Chapel function. See docs/source/examples/test_finance_chapel_numpy.py

Note that some pyChapel tests, test_pych_reduce_add.py and test_chapel_slicing_inline.py, work
in spite of this change.

When this issue is closed, please also close the corresponding Chapel issue