more fixes on gcc warnings, misleading indentation and CPU mitigation when the traffic demand in 5G exeeds the available througput

- In case no signal is received then energy of ULSCH is zero,
  the phy_procedures_gNB_uespec_RX will return 1 as an error.

changed DCI candidates to 4 for initialDownlinkBWP ue-specific searchSpace. ulsch/pusch stats added to nrL1stats.log

added n1L1_stats.log. improvements to noise level (PUCCH/PUSCH) and signal level (PUCCH) computations. added DTX detection parameters for PUCCH/PUSCH/PRACH in L1 section of configuration file. hotfix from C. Roux for SRB PDCP integrity. extra logging to debug missing PUSCH/DCI at UE.

- new function has been introduced for the computation of UL SNR
- minor bugfix to noise power computation
- FAPI data type for referenceSignalPower has been updated to reflect the
  range of values for the SSB power

- CDM groups used, multiple DMRS locations tested
- REMOVED compiler define NR_SC_FDMA
- enabled -Z option in ulsim for testing NR SC-FDMA
- Gnb UL Processing of LLRS even if last symbol allocated has no data
- transform precoding Enumerations used

- Most DL code is reused for Ul also to reduce code duplication
- Common CPE calculation function is used for error estimation
- Common slot processing function is used for inter/extrapolation
- Removed old implementation dedicated to UL

This commit contains work done by Eurecom and by Benetel.

After the UE disconnects, the next connection fails
because the gNB cannot decode Msg3. The root cause
seems to be this ul_valid_re_per_slot not set to 0.
Setting it before the test fixes the problem and
does not seem to impact anything else.