Conversion of ONNX End-to-End

[kells1986]

I added some simple functionality to convert and end-to-end pipeline to ONNX.

It works for ONNX, but coreml is giving me some issues with unsupported ops.

[vietanhdev]

You can use SAM Exporter to export Encoder and Decoder separately: https://github.com/vietanhdev/samexporter.

[ChaoningZhang]

Thanks for your interest in our work. My team members have implemented ONNX conversion and now this branch has conflicts. Therefore, we decide to not integrate it. Thanks for your interest again~~

[kells1986]

No problem, I'll take a look at the new implementation. Thank you for sharing this excellent work.