NR_UE: Perform autonomous timing advance to compensate for fast time drift with relatively large RTT

As we don't have SIB19 with continuously updated ta-Common and ta-CommonDrift values yet, the UE can only adapt it's UL timing according to it's DL drift.
This is required for the UE to keep UL sync with fast time drift and relatively long RTT (e.g. LEO satellite).
We should replace this with the standard compliant way as soon as we have SIB19 with continuously updated contents.