The MasterInformationBlock is handled at the DU and sent to the CU in
the F1 Setup Response. Hence, move it down to the MAC. Furthermore:

- Change type because MIB_PDU_t is 4G type
- Simplify schedule_nr_mib()

nr_DRB_preconfiguration() does a "pre-configuration" for the default DRB
for "noS1" mode, i.e., when there is no connection to core network. In
this case, there is no PDU session to be set up, and hence we need to
preconfigure the DRBs.

We replace this function with partially existing functions and a new
function fill_nr_noS1_bearer_config() which returns a bearer
configuration for the noS1 case, also better reflected in the function
name. It has also been moved to asn1_msg.c, away from the actual PDCP
layer.

Creates function that have nr_pdcp_ prepended to their name, and change
the signature of some functions for the 5G PDCP:

- nr_pdcp_layer_init()
- nr_pdcp_data_req()
- nr_pdcp_remove_UE()
- nr_pdcp_config_set_security()
- nr_pdcp_remove_UE()
- Make separate functions for nr_pdcp_data_req_srb/drb()

Removes phy_procedures_gNB_common_RX() (only used in nr_ulsim) + fixes
in pucchsim