- this patch moves common code shared between multiple UE types, i.e.,
UEs for different RATs into a commong base class
- it also introduces a switch during UE startup to instantiate the
selected UE type
- this patch changes the UL harq config to a dedicated one
instead of passing the whole MAC config which may be specific to
a specific RAT
- it also extends the RRC to fill the harq specific config field in the
MAC config
- clean up dl_harq and remove unused mac config