Refactor F1 Setup Req/DU config update: transport slices via F1 and read config

In the DU, read slice information from the DU config file. Handle
multiple slices within the F1 Setup Request structure representation,
and forward it via F1 to CU. The DU slice information is stored in the
setup request structure.

openair2/COMMON/f1ap_messages_types.h

@@ -129,10 +129,9 @@ typedef struct f1ap_served_cell_info_t {
   /* Tracking area code */
   uint32_t *tac;
 
-  // Number of slide support items (max 16, could be increased to as much as 1024)
+  // Number of slice support items (max 16, could be increased to as much as 1024)
   uint16_t num_ssi;
-  uint8_t sst;
-  uint8_t sd;
+  nssai_t nssai[16];
 
   f1ap_mode_t mode;
   union {