Use F1 internally: RRC Message Transfer

First MR in a series of changes to use the F1 interface internally at the gNB.

• RRC Reject not handled yet via F1 message exchange
• Removes ITTISIM (which does not compile)
• Refactors code duplication of linear allocator of gNB/eNB RRC

common/utils/ocp_itti/intertask_interface.h

@@ -308,6 +308,7 @@ void *rrc_enb_process_msg(void *);
   TASK_DEF(TASK_RLC_ENB,  TASK_PRIORITY_MED, 200, NULL, NULL)   \
   TASK_DEF(TASK_RRC_ENB_NB_IoT,  TASK_PRIORITY_MED, 200, NULL, NULL) \
   TASK_DEF(TASK_PDCP_ENB, TASK_PRIORITY_MED, 200, NULL, NULL)   \
+  TASK_DEF(TASK_PDCP_GNB, TASK_PRIORITY_MED, 200, NULL, NULL)   \
   TASK_DEF(TASK_DATA_FORWARDING, TASK_PRIORITY_MED, 200, NULL, NULL)   \
   TASK_DEF(TASK_END_MARKER, TASK_PRIORITY_MED, 200, NULL, NULL)   \
   TASK_DEF(TASK_RRC_ENB,  TASK_PRIORITY_MED,  200, NULL,NULL)\