[ROCm] add support for ROCm/HIP

[jeffdaily]

• do not use THC.h or THH.h or THCState
• rename files to avoid collisions at build time due to hipify
• HIP host device definitions in tensorview.h
• use HIP atomicAdd() in scatter_points_cuda.cu
• add WITH_ROCM anywhere WITH_CUDA was used
• update setup.py for renamed files and ROCm/HIP torch