add initial NTN support for gNB

For the initial NTN support for gNB, this is modified:

• add NTN specific parameter cellSpecificKoffset_r17 and use it for UL scheduling
• change TA update interval to 100 frames instead of 10
• fix phytest scheduler in case no HARQ processes are available
• make checks for missed feedbacks more robust w.r.t. frame number warp-around in find_harq()
• use 2 * K2 for contention_resolution_timer, as the timer starts with Msg2 transmission and ends with Msg4 ACK reception
• add sr_ProhibitTimer_v1700
• make SR timers configurable in CONF file
• make ue_TimersAndConstants configurable via conf file

This is part of the work developed by Fraunhofer IIS within the ESA-funded project 5G-GOA (https://connectivity.esa.int/projects/5ggoa).