[BUG] Support DCNv2 operator

[Fvoiretryzig]

🐛 Bug

There is no support for DCNv2 operator. I want to use nnfusion to optimize a model which I convert it from pth form to onnx form, however there is no support for DCNv2 operator. I use this script to turn the model into onnx form.
I found nnfusion can add custom op and I added it following the tutorial in this page. When I recompiled nnfusion and test on a model, it also appeared there was no DCNv2 operator.

src/nnfusion/frontend/onnx_import/util/graph_convert.cpp 530    No translator for DCNv2, try to convert to generic op

I want to know how I can add this operator in nnfusion. Should I add some files such as DCNv2.cpp in onnx_import/op file?

[mzmssg]

@Fvoiretryzig Could you share how you added custom op, by c++ or Json? Did you regenerate cmake files when recompiling nnfusion?