Enable multiple RC subscriptions

- create hash table to save ric_req_id (key) and array of ran_param_id(s) (values), per each subscription
  - create RB tree to store list of ric_req_id(s) for each ran_param_id
    => when the async event occurs, it is easier and faster to search per ran_param_id and send the indication message to all xApps (ric_req_id(s)) subscribed to the same ran_param_id
  - it is important to mention that both data structures need to be maintained, especially when unsubscription occurs (free_aperiodic_subscription)

openair2/E2AP/RAN_FUNCTION/O-RAN/ran_func_rc.h

@@ -24,13 +24,12 @@
 
 #include "openair2/E2AP/flexric/src/agent/../sm/sm_io.h"
 
-bool read_rc_sm(void *);
-
 void read_rc_setup_sm(void* data);
 
-sm_ag_if_ans_t write_ctrl_rc_sm(void const* data);
-
 sm_ag_if_ans_t write_subs_rc_sm(void const* src);
 
-#endif
+sm_ag_if_ans_t write_ctrl_rc_sm(void const* data);
 
+bool read_rc_sm(void *);
+
+#endif