feat: Add import session API in the fast API

PiperOrigin-RevId: 771279971

src/google/adk/cli/fast_api.py

@@ -412,12 +412,19 @@ def get_fast_api_app(
       app_name: str,
       user_id: str,
       state: Optional[dict[str, Any]] = None,
+      events: Optional[list[Event]] = None,
   ) -> Session:
     logger.info("New session created")
-    return await session_service.create_session(
+    session = await session_service.create_session(
         app_name=app_name, user_id=user_id, state=state
     )
 
+    if events:
+      for event in events:
+        await session_service.append_event(session=session, event=event)
+
+    return session
+
   def _get_eval_set_file_path(app_name, agents_dir, eval_set_id) -> str:
     return os.path.join(
         agents_dir,