Add assembleStorage and disassembleStorage methods for CSR

[KyleVaughn]

Description:

The "assembleStorage" and "disassembleStorage" methods are intended to be added to the CSR (Compressed Sparse Row) class. These methods will facilitate the conversion of data from the base class SparseMatrix into a format that is compatible with the CSR storage format. CSR is a commonly used data structure for representing sparse matrices efficiently.

Tasks:

• [ ] Create a method named "assembleStorage" within the CSR class that takes necessary input arguments from SparseMatrix.
• [ ] Iterate through the existing data in the SparseMatrix and organize it into three vectors (that should already be variables of the CSR class): values, rowPointers, and columnIndices
• [ ] Create a method named "disassembleStorage" within the CSR class that takes input arguments from the CSR format.
• [ ] Convert the CSR format back into the format used by the base class SparseMatrix so the reverse of the assembleStorage method.
• [ ] Develop a set of unit tests to ensure the correctness of both the "assembleStorage" and "disassembleStorage" methods. Test various scenarios, including different matrix shapes, sparse patterns, and edge cases.

Definition of done:

Unit tests for both methods pass successfully, covering a variety of test cases and edge cases.

[KyleVaughn]

Review by @AshrayMohit

[AshrayMohit]

Complete implementation with accurate and descriptive tasks, well done.

[lwh1106]

Hi, the CSR class has been added to the "csr" branch. Feel free to use it, and just let me know if there are any bugs ...