Integration 2020 wk45 (2) comprising:

MR937:Nr dl sched fixes  
-restore old phytest scheduler behavior
-correct TA scheduling
-correct SSB
-shorten interface of `nr_fill_nfapi_dl_pdu()`
-Track RB allocation on symbol basis (bitmap)
-add a `remove_nr_ue_list()`, could be used instead of MR !934

MR910:5G SA NAS messages 
- 5G SA nass messages and a simple unitary test code
 
MR927:Nr rrc configuration fr2
- introduces some bug fixes for FR2 that might also have an impact on FR1.

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

 Conflicts:
	openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c

The SSB nFAPI message is only sent every 8 frames, and automatically
repeated by the PHY layer in between. This commit sets the vrb_map
structure in those frames in between nFAPI so that the scheduler does
not schedule on such resources.

The phytest preprocessor schedules only one UE, as many RBs as possible
(largest continuous RB region), with a fixed MCS and time domain
allocation.

MR902 Nr mac ssb ro ue idcc
- Construction of SSB-RO mapping table on the UE
- RO selection based on SSB index
- RACH preamble selection based on SSB index in a selected RO
- RA-RNTI calculation
  

MR928 nr: add MAC PDU traces for wireshark
- The T tracer macpdu2wireshark has been modified to handle the new traces. The usage is the same as for LTE.  

MR929 RA fixes for NR UE  

MR938 CI: Parse UE TUN interface correctly in S1 mode
- The TUN interface configuration is changed to use program "ip" only. 
- The CI script parsing is changed accordingly: the pipeline will recognize the attempt to bring up the interface of the first UE.

MR933 nr rlc: bugfix 
- ret.next was not set in a particular case

See also commit 8c5976e2

Above commit changed the TUN interface configuration to use program "ip"
only. This commit changes the CI script parsing correspondingly: the
pipeline will recognize the attempt to bring up the interface of the
first UE.

Merge branch 'NR_RRCConfiguration_FR2' of http://gitlab.eurecom.fr/oai/openairinterface5g into NR_RRCConfiguration_FR2