Distinguish weak and strong CSC/CSR formats

[rileyjmurray]

RandBLAS' coo-to-cs[c/r] functions ensure a strong sorting property where indices within each compressed vector (column/row) are sorted. This format isn't strictly required in most definitions of CSC and CSR formats, and it's only loosely implied by the definitions we state in our documentation. We should make some changes to reflect this situation.

1. Have helper functions for determining whether a compressed sparse matrix is strongly sorted.
2. Have helper functions to modify a compressed sparse matrix in-place to ensure strong sorting.
3. Have sufficient-condition flags on compressed sparse matrices to indicate that they're guaranteed to be strongly sorted.

[rileyjmurray]

Point 1 is (mostly) handled by sparse_data/base.hh::compressed_indices_are_increasing, which was merged with the addition of sparse TRSM.