e3ap: add E3 agent lifecycle and nr-softmodem init hook

Add the E3 agent lifecycle on top of libe3: configuration mapping,
agent creation/init/start, dApp report and status-change handlers,
and xApp control and subscription-query helpers. Wire e3_init() and
e3_destroy() into nr-softmodem under the E3_AGENT guard.

The agent registers no concrete service models: service models (such
as spectrum sensing) live in their own modules and register
themselves, keeping the framework decoupled from any specific use
case.

Signed-off-by: Andrea Lacava <thecave003@gmail.com>

executables/nr-softmodem.c

@@ -19,6 +19,11 @@ unsigned short config_frames[4] = {2,9,11,13};
 #include "openair2/E2AP/flexric/src/agent/e2_agent_api.h"
 #include "openair2/E2AP/RAN_FUNCTION/init_ran_func.h"
 #endif
+
+#ifdef E3_AGENT
+#include "openair2/E3AP/e3_agent.h"
+#endif
+
 #include "nr-softmodem.h"
 #include <common/utils/assertions.h>
 #include <openair2/GNB_APP/gnb_app.h>
@@ -521,6 +526,13 @@ int main( int argc, char **argv ) {
 
   softmodem_verify_mode(get_softmodem_params());
 
+//////////////////////////////////
+//// Init the E3 Agent
+#ifdef E3_AGENT
+  printf("Init E3 Agent\n");
+  e3_init();
+#endif // E3_AGENT
+
 #if T_TRACER
   T_Config_Init();
 #endif
@@ -727,6 +739,11 @@ int main( int argc, char **argv ) {
 
   time_manager_finish();
 
+#ifdef E3_AGENT
+  printf("Destroy E3 Agent\n");
+  e3_destroy();
+#endif // E3_AGENT
+
   free(pckg);
   logClean();
   printf("Bye.\n");