Add control_variate for VlasovMaxwell Model

• Add control_variate for VlasovMaxwell model
• Format many files, add if rank==0 to some print statements
• Add class L2_Projector in struphy.psydac_api.geom_projectors.py
• Add function add_option ass class-method for StruphyModel base class, more slick than adding every dict by hand