- a new section in the configuration file to select security algorithms,
  with new code to deal with it
- cleanup CG-ConfigInfo: specs seem to indicate that we must not
  add mcg_RB_Config; the gNB has to deal with that
- as a consequence, modify fill_default_rbconfig() that is called in
  every cases and needs security and bearer parameters

The new section in the configuration file looks like:

    security = {
      # preferred ciphering algorithms
      # the first one of the list that an UE supports in chosen
      # valid values: nea0, nea1, nea2, nea3
      ciphering_algorithms = ( "nea0", "nea2" );

      # preferred integrity algorithms
      # the first one of the list that an UE supports in chosen
      # valid values: nia0, nia1, nia2, nia3
      integrity_algorithms = ( "nia0" );
    };

1. Changed rx gain at gNB from 75 to 50. PUCCH works again with OAI-UE.
2. Disabling MAC layer retransmission logs.

Improvements to decode SIB1 in 3rd party implementations and OAI UE with the same gNB configurations

The thread count would me minimum of (no of cores in the machine) or (parameter mentioned in config file)