separate K and J from Fock matrix calculation in RHF

**Short description** Separate the calculation of the Coulomb and Exchange matrix from the function that calculates the Fock matrix in RHF. **Related issues** [Coulomb and Exchange matrix python bindings ](https://github.com/GQCG/GQCP/issues/1091) **To do** - [x] Create a function for caluclating the Coulomb matrix in RHF in cpp code - [x] Create a function for calculating the Exchange matrix in RHF in cpp code