Copy of matrix values without allocating new memory space

[SylvestreSakti]

Describe the current behavior

Currently, there is no method for Matrix objects (especially DenseMatrix) that lets the user copy values from one matrix to another without allocating new memory for a new matrix.
This can lead to overconsumption of memory space when dealing with large matrices.

Describe the expected behavior

It is expected to have a copyValues(originalMatrix, copyMatrix) method in DenseMatrix that can copy the values from the originalMatrix to the already existing copyMatrix (the dimensions of the matrices should be the same).

Describe the motivation

This need follows this PR in OpenLoadFlow : powsybl/powsybl-open-loadflow#1109

In this PR, a local method has been implemented to copy the values of a DenseMatrix but a clean way would be to have this method directly in powsybl-core.

Extra Information

No response