Create sparse matrix with contiguous memory for MatrixMarket.

The current behavior (allocating each row separately ) is rather surprising and unnecessary as the matrix market file stores the number of nonzeros anyway. Hence we now pass this number to BCRSMatrix::SetSize to get the most efficient behavior.

Note that currently the only way to get a matrix with contiguous memory is to copy it.

enabled an automatic merge when the pipeline for 7b8d189d succeeds

merged

mentioned in commit 729ec611