gRPC interceptor to transform kubernetes errors to gRPC errors

[jessesuen]

We should have an gRPC interceptor which translates kubernetes errors into the corresponding gRPC codes. The interceptor would have logic like:

apierr "k8s.io/apimachinery/pkg/api/errors"

if apierr.IsNotFound(err) {
    err = grpc.Errorf(codes.NotFound, err.Error())
} else if apierr.IsAlreadyExists(err) {
    err = grpc.Errorf(codes.AlreadyExists, err.Error())
}

[merenbach]

WIP in https://github.com/merenbach/argo-cd/tree/convert-errors