Replace SparseMatrixDescriptor by CRSMatrixDescriptor

The new class is meant to be much faster

• it requires an estimation of the number values per row
• if the number of stored values per line exceeds the reserved one, an a special storage zone (per row) is used.

It is important to give a precise estimation of the number of values per rows:

• if the provided expected number of values is too small with regard to the real number of values stored for a given row, then building performances can be noticeably affected
• if the provided expected number of values per row corresponds exactly to the effective number of stored values, then the construction of the CRSMatrix costs nothing.

In the later case, one benefits from a significant CPU and memory costs reduction.

assigned to @delpino

approved this merge request

enabled an automatic merge when the pipeline for 34459135 succeeds

mentioned in commit 1ee877f7

merged