Add HarmonyOS demo for Kokoro TTS 1.0

[csukuangfj]

It throws the following error since HarmonyOS in sherpa-onnx uses onnxruntime 1.16.3.

LastFatalMessage:terminating due to uncaught exception of type Ort::Exception: 
Failed to load model with error: /home/runner/work/onnxruntime-libs/onnxruntime-libs/onnxruntime/onnxruntime/core/graph/model_load_utils.h:56 
void onnxruntime::model_load_utils::ValidateOpsetForDomain(const std::unordered_map<std::string, int> &, const logging::Logger &, bool, const std::string &, int) 
ONNX Runtime only *guarantees* support for models stamped with 
official released onnx opset versions. Opset 20 is under development
 and support for this is limited. The operator schemas and or other functionality 
may change before next ONNX release and in this case ONNX Runtime 
will not guarantee backward compatibility. Current official support for domain ai.onnx is till opset 19.

We need to re-export the onnx model using a lower opset.