[FEA] Expose `count_multi_edges ` for cuGraph C++ graph_view_t to python

[VibhuJawa]

Describe the solution you'd like and any additional context

We should expose count_multi_edges for cuGraph C++ graph_view_t to python to check if a graph has multi_edges.

It is possible for that it can be used to has_duplicates in Property Graphs.
Currently we do expensive has_duplicates call here and using that count_multi_edges might be more optimial.

For more context see discussion here