Multipolar expansion in PZW Hamiltonian

Description

Enable magnetic dipole and electric quadrupole terms in coupling Maxwell with electrons. This implies that for the first time we need to get 2 types of fields from Maxwell partners to the electrons, which demanded splitting the single interaction we had before (used for E-field and vector potential, depending on a "type" attribute) to different routines for different quantities.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.