- now done according to the proper DL/UL frequency
- this makes it compatible with FDD mode

Enabling more numerology combinations and 100 MHz support with 3/4 sampling for USRP X300/X310, too.

- skipping RA procedures when MAC is disabled
- added mac_enabled flag that allows to disable RA and TA at UE from CL

- moved configuration of UE parameters to set_options function
- removed redundant loop over CCs

- removed redundant initialisation of variables
- introduced two "RF helpers" function that are replacing shared code in the sync routines
- added a new .c file and updated the cmakelists and .h files

- got rid of global variable fp
- code cleanup, removed redundant and unused code
- removed unused command line options and variables
- grouped command line setting in set_options function

- this reflects the implementation of IF and IF offset in the gNB RU
- the RF frequencies are set at HW level while the target frequencies are
  stored in fp, therefore the values stored in fp should not be changed
  after sync as only the tx/rx freq is updated
- removed overwritten dl/ul carrier frequencies in fp after sync
- removed redundant set of tx/rx freq in ue_synch (done in init_openair0)
- removed irrelevant set of dl/ul carrier freq in get_options

This commit contains work done by Eurecom and by Benetel.

implementation of missing symbol-based rotation for NR modulation/demodulation (Section 5.3 38.211). Tested with unitary simulators (ulsim/dlsim).
To be tested with gNB testbench and rfsimlator