What is the expected enhancement?

Right now we have the vf2_mapping() function which iteratively returns the isomorphic mappings found by the vf2 algorithm to python space. It would be great to expose this functionality from rustworkx-core too for rust users so given any two generic graph objects we can get an iterator of mappings of node indices between them which are isomorphic. We should look into how we can port the https://github.com/Qiskit/rustworkx/blob/main/src/isomorphism/vf2.rs module into rustworkx-core so we can expose all the vf2 and vf2++ heuristic functionality to rust users too.