Integration 2020 wk48 2

MR945 : Nr prach fr2
MR971 : Correct NDI + Minor MAC subPDU handling improvements (repair TA)
MR972 : Bugfix nr rate matching assertion
MR950 : DL and UL PTRS for 5G NR
MR975 : File openning in rrc_gNB_internal
MR977 : NR UE DCI sanity checks and fixes
MR970 : uci gnb mac functions file