CI: Improve OAI UE testing with USRP
Now:
- When launching the OAI UE w/ USRP board, the initialize function tries to detect if the cell synchronization occurs
- If yes, it kills the ue softmodem process (if still present) and relaunches again
- This applies to sniffing test-cases and connection test-cases
- We also check that the oaitun_ue1 interface is up and configured
- We support finally a w/ S1 configuration
- Added XML scenario files w/ start and stop of EPC
- new FDD-5MHz scenario w/ ping and iperf from/to UE to/from EPC