Final --phy_simulators warning removals for this branch, and former polar coding function corrections

first version of UE FAPI handling for DLSCH. paramters from DCI are now handled by MAC and passed back to the PHY to program PDSCH. Still need to check parameters and take them into account in PHY.

- UE channel estimation no longer done in slot_fep. Also created dedicated memory for channel estimates of different channels
- using nr_extract_dci_info instead of nr_generate_ue_ul_dlsch_params_from_dci as in phy_procedures_nr_ue. The latter was only a (poor) wrapper and not doing what the name suggests. also with FAPI things have to be done differently now. This will come in a next commit.
- other minor changes to remove warning
prepreatory changes

This reverts commit 61e36839.

adding function dci_req for UE
disabling handle_dci for now

BWP information in NFAPI gNB/UE
dci encoding / decoding integrated
DCI decoding still fails

nr-UE: bugfixes
pbchsim: adding options to input/output signal files

Still a remaining issue with the SNR normalization, way too low to get errors.

0. unwiring of 40 MHz channel hard-coding and general SSB location
1. PSS dynamic range improvement and DC carrier fix
2. SSS channel estimation and detection corrected
3. PBCH channel estimation fixed
4. PBCH channel extraction/compensation reworked for the general case
5. fixed-point low-complexity polar decoder integrated to PBCH decoding chain

works by default (nr_pbchsim) at 100 MHz / 30 kHz SCS and SSB wherever (but known to UE)