[FEA] Change mutual_reachability_graph to use device_sparsity_owning_coo_matrix

[benfred]

We should update the mutual_reachability_graph function to use the device_sparsity_owning_coo_matrix instead of the older COO class that it is using now.

This will require some updates to sparse algorithms in RAFT, such as raft::sparse::linalg::symmetrize and raft::sparse::convert::sorted_coo_to_csr - which only accept the raft::sparse::COO class.

See #323 (comment)