The name NR_UE_list_t is misleading: beyond being a simple "list", this
structure carries all/most UE-related MAC information. If at all, it is
a container for multiple lists. The next commit introduces a
NR_UE_list_t structure that organizes UEs in lists such that it is
easier to go through the UEs.

nr_configure_pdcch() allocates the CCE, but this is not wanted, e.g., in
multi-user scheduling, since it might not be possible to allocate the
CCEs for these UEs. This commit makes the following changes:

- remove CCE allocation in nr_configure_pdcch()
- remove coreset search in nr_configure_pdcch()
- add functions get_coreset() and get_searchspace() to retrieve coresets
  and search spaces easily
- in nr_fill_nfapi_dl_pdu(), add extra parameters for aggregation level
  and CCE indices and the searchspace and coreset of a UE, which might
  be different for each UE
- allocate CCEs manually in phytest, RA, and DLSCH schedulers

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

This commit contains work done by Eurecom and by Benetel.

- LDPC decoder does not support lower MCS, therefore MCS 9 has been selected
  for the Msg2 configuration.
- This is done only in do-ra mode, in order to prevent any fallout on the
  current the configuration used for the operation with the commercial UE

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

This reverts commit 1462f0e6.

modifications for DCI size of format 1_0 for RAR and filling of FAPI for RAR according to special RAR-related configuration

added FAPI interfaces int gNB prach receiver functions (rx_nr_prach,rx_nr_prach_ru) and in indication to MAC.