Fix Coverity Scan CID 340209 (Variable message_p going out of scope leaks the storage it points to.)

Fix Coverity Scan CID 340277 (Variable gNB_CUSystemInformation going out of scope leaks the storage it points to.)

- add message sender (CU) + handler (CU) and fill with data from ITTI message
- add PLMNID_TO_MCC_MNC and BIT_STRING_TO_TRANSPORT_LAYER_ADDRESS_IPv4 macros
- correct TRANSPORT_LAYER_ADDRESS_TO_BIT_STRING:
  change name to TRANSPORT_LAYER_ADDRESS_IPv4_TO_BIT_STRING, make it send 4B, not 5

Connection goes until generation of RRCConnectionSetup in CU which crashes (it calls rrc_mac_config_req. For DU this should be replaced with filling DL_RRC_MESSAGE_TRANSFER