Properly return data from non-contiguous tensors in Java
Summary:
These were returning incorrect data before. Now we make a contiguous copy
before converting to Java. Exposing raw data to the user might be faster in
some cases, but it's not clear that it's worth the complexity and code size.
Test Plan: New unit test.
Reviewed By: IvanKobzarev
Differential Revision: D19221361
fbshipit-source-id: 22ecdad252c8fd968f833a2be5897c5ae483700c
