Merge branch 'NR_MAC_SSB_RO_GlobalEdge' of https://gitlab.eurecom.fr/oai/openairinterface5g into NR_MAC_SSB_RO_GlobalEdge

Integration branch 2020 week 30  

- MR 854 : NR_DCI_01  
- MR 857 : improve_ue_stability  
- MR 839 : mac-flexran-improvements

Oai integration week29

See merge request oai/openairinterface5g!858

Use LFDS 7.0.0 Ringbuffer implementation to handle
* Slice Configuration
* UE slice association
which is then uploaded through MAC scheduling thread

Selects the UE with the highest CQI. If two UEs have the same CQI,
choses the one with highest number of bytes in RLC queue. Allocates as
many RBGs as possible, and potentially continues with the next UE.

Selects UE with highest coefficient. Allocates until there are no more
RBGs to allocate, or UE has no more data. In the latter case, continues
with the next UE (second-highest coefficient).