Adding operators= to CartDecomposition and subclasses

openfpm_vcluster

src/Decomposition/CartDecomposition.hpp

src/Decomposition/CartDecomposition_unit_test.hpp

src/Decomposition/common.hpp

src/Decomposition/ie_loc_ghost.hpp

src/Decomposition/nn_processor.hpp

src/Grid/grid_dist_id.hpp

src/Grid/grid_dist_id_unit_test.hpp