Split grpc to a separate package

[AkihiroSuda]

Because a downstream project may not always want to depend on gRPC

[austinvazquez]

@AkihiroSuda , if you can create the repo (assuming a seperate repo), I can help porting the gRPC code over. Maybe containerd/grpc-errs or something better named 😅 ?

[AkihiroSuda]

I don't think we have to split the repo

[akhilerm]

+1 to what @AkihiroSuda said. Creating a new repo for the gprc errors would be too much. We can have a separate package for grpc errors in the same errdefs repo.

[austinvazquez]

Ah I mistook the intent. A seperate package would be compiled out if users did not need it. I can open a PR on this and get your feedback.