Add the onnxsim support

[LRY89757]

Hi, onnxsim is a wonderfull onnx graph optimizer. I think it may be useful for the deploy of topformer! It could remove some unuseful ops in onnx graph and sometimes accelerate the computing. After the simplifying, the model could support more deploy ways, like ncnn, etc.

[gordinmitya]

don't forget to test if model still can perform with various input sizes