An alternative route of Julia interface

[yebai]

MS PyNative mode seems to provide functionality similar to PyTorch. It allows dynamic graph construction without first building a graph. If that is the case, can we

1. create a Julia wrapper for PyNative APIs using PyCall?
2. Furthermore, is there a C API for the MS PyNative methods? If so, we can avoid the python overhead by calling into C API directly (similar to ThArrays).

In the simple case (1), it would be helpful to quickly verify whether it is a viable approach. We can look at case (2) at a later point.