merge dev GW embedding (includes other fixes as well)

[the-hampel]

• new gw_flow module to run gw_embedding with the AIMBES code
• switch from old ctseg to new ctseg_j solver and make changes in solver structure
• add new DC schemes 'crpa_static', 'crpa_static_qp', 'crpa_dynamic'
• use cRPA calculated Uijkl as interaction via 'crpa', 'crpa_density_density', 'dyn_density_density', 'dyn_full' hint types
• new gw params section in input passed to all functions
• update doc to reflect these changes
• allow CRM Dyson solver for both cthyb and ctseg to obtain Sigma_imp from G_tau
• add new tests for CRM Dyson solver (requires triqs 3.3)
• add new GW embedding tests that run optionally with -DTest_GW_embedding=ON
• use cmake variable to determine max number of mpi ranks during testing