This reverts commit 1462f0e6.

- Updated PRACH procedures and general code formatting
- gNB msg1 handling and RAR generation
- general bug fixing
- formatting
- missing headers
- RAR handling.

build improvements: allow build mode selection (-g -G options) allow all exec build in one pass, remove remaining USE_MME macros in nr code

Mainly comestics and integer type management
Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

 - gNB now only sends samples to USRP when DL slot. (should do the same for UE)
 - increased sf_ahead to 6
 - fixed timestamp for usrp_write at UE

 - gNB now only sends samples to USRP when DL slot. (should do the same for UE)
 - increased sf_ahead to 6
 - fixed timestamp for usrp_write at UE

ENDC: Add X2AP initial configuration and X2AP task in nr-softmodem. Small issue with parsing NRCCPARAMS_DESC from RCconfig_NR_X2() needs to be resolved

Conflicts:
	openair2/GNB_APP/gnb_config.c

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