-Also change the place of the check on whether x2ap is enabled to trigger the ITTI tick message from RRC to X2AP.

This commit introduces several enhancements in X2AP and RRC to deal
with ENDC. The main goal is to deal with UE's on/off and with various
errors.

The following work is included:

    - DC prep and DC overall X2 timers
    - X2 messages for UE release and DC timers' timeout

Open problems:

    - what to do when the UE sends an scg Failure? This commit removes
      the UE. And this removal may not be correctly done
    - UE removal in the gNB's PHY layer (a next commit is coming,
      but it is hackish and will need a rework)

ENDC path switch S1-U: Integrated S1AP E-RAB-Modification indication message at eNB, interfacing with RRC and X2AP to get proper configuration of E-RABs to be modified and GTP-U configuration at gNB

ENABLE_ITTI macro removal, modified telnet server to support all executables, modified record player to finalize switch to run-time option and allow usage with any device

UE-Capability parsing for NR components. Emulate CG-ConfigInfo generation for phy-test mode. This version is ready for X2 EN-DC integration

remove RRC_VERSION macros, simplify build-oai and CMakefile.txt accordingly, get rid of remaining compilation warnings (opt module improperly merged and patch asn1c files with tests against max 64 bits integer value)

- reworked configuration file and configuration for gNB (write directly to ASN1 structure from config module instead of passing intermediate structures)
- added prach procedures for gNB with configuration of PRACH L1/L2 parameters

phy_simulators do compile, but dlsim&nr_(ulsch/dlsch/pbch)sims do not pass tests + Raphael's CI patch applied.

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