Add scheduled tasks (#13470)

### What problem does this PR solve?

1. RAGFlow server will send heartbeat periodically.
2. This PR will including:
- Scheduled task
- API server message sending
- Admin server API to receive the message.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/cpp/Makefile

@@ -51,7 +51,7 @@ c_api_debug: $(BUILD_DIR)
 
 # Test the Go bindings
 test_go: c_api
-	cd bindings/example && go run main.go ../../$(BUILD_DIR) "这是一个测试文本。This is a test."
+	cd bindings/example && go run main.go ../../$(BUILD_DIR) "This is a test."
 
 # Run memory test
 test_memory: c_api