[oneMKL][SpBLAS] Add nnz arg to oneapi::mkl::sparse::set_csr_data() API

[gajanan-choudhary]

Changes

• Adds intType nnz argument to oneapi::mkl::sparse::set_csr_data() API.
• Changes num_rows, num_cols to nrows, ncols, to also avoid using num_nz instead of nnz that we are proposing.
• Updates CSR matrix description with nnz definition, usage.

Need

• cuSPARSE contains an nnz argument in their cusparseCreateCsr() API. Adding the cuSPARSE backend when implementing the oneMKL specification will require workarounds if the nnz argument is not added to the specification. In most cases, nnz is known (except when it is being found as part of the API such as sparse + sparse = sparse or sparse * sparse = sparse matrix operations, but note that such APIs are currently not part of the oneAPI/oneMKL specification.)
• We would like this change to be part of the oneMKL spec version 1.3 that's to be released soon.

[spencerpatty]

pending decision about const or no on sizes, I approve.

[gajanan-choudhary]

@rscohn2, @mkrainiuk, could one of you please merge this PR in by EOD today so it can go into spec v1.3? @spencerpatty reached out to me and said he might be unavailable today to merge the PR in.