Add copy as grpcurl for grpc requests

[fleytman]

Now in proxyman i can copy as curl, but it dosn't support grpc calls. Pls add copy as grpcurl for grpc requests

[NghiaTranUIT]

Can you give me an example of how Copy as grpcurl looks like 🤔

[NghiaTranUIT]

Not sure if it works since the body of gRPC is serialized as a Protobuf format, and Proxyman doesn't officially support it.

[fleytman]

Grpc can use compiled protoset and grpcurl can it import:https://github.com/fullstorydev/grpcurl#protoset-files