Revision for the STRUPHY_cc_lin_6D_matrix_free

List of corrections : - hylife/utilities_FEEC/projectors/mhd_operators_3d_global_V2.py tests/tes_mhd_projectors.py New projection operators S10, K10, Z20, Y20 and S20 are added to handle both p 0-form and 3-form. Projection operator X1 and X2 are fixed. Test codes are also fixed to cover the described additions and corrections.

- simulations/run_STRUPHY_cc_lin_6D_matrix_free.sh simulations/STRUPHY_cc_liin_6D_matrix_free.py simulatinos/.../initial_conditions_MHD.py hylife/utilities_FEEC/projectors/mhd_operators_3d_global.py The notation p3 and r3 are replaced with pp and rp to cover all the cases of forms for pressure and rho. Small additions which is needed to handle p 0-form cases.

- hylife/utilities_FEEC/projectors/projectors_global.py hylife/linear_algebra/linalg_kron.py dofs_mat and dofs_T_mat are added for the new routine of calculating dofs using Q matrix New kron matvec routines are added.