CUDA Codegen Error

[sancierra]

Compiling the CUDA SDFG below yields a codegen error (dace::GlobalToGlobal cannot be found)

global_to_global_bug.sdfg.zip

Instead of generating GlobalToGlobal in dace/codegen/targets/cuda.py, we should raise a NotImplementedError that mentions that GPU global memory to global memory copies need to be more explicitly specified in the code.

To reproduce this (and we should add a test), we can add a GPU_Global access node outside and a GPU_Global access node inside a GPU_Device map.