Merge branch 'integration_2020_wk45_2' into 'develop'

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.