Explore tensordict for handling the dict of tensors in cugraphDGL and cugraphPyg

[VibhuJawa]

We should explore https://pytorch.org/tensordict/ , we currently have a lot of work around handling dict of tensors and i think we can benefit by using this framework.

TensorDict is a dictionary-like class that inherits properties from tensors, such as indexing, shape operations, casting to device , making those things much easier/simpler.

CC: @alexbarghi-nv , @tingyu66 , @BradReesWork