Bring your own Proto files

[nleiva]

Now that the vendor folder is gone and we are using Go modules, we can import XR YANG proto files from any repo we want to. Still thinking how we could provide this as a functionality to the user, but all we need to do, to bring a different set of proto files is to modify the importing path of codec_gpb.go, xport_grpc_test.go, pipeline.go, etc. to point to a repo other than github.com/cisco/bigmuddy-network-telemetry-proto. Then compile again.

import (
        ...
	telem "github.com/cisco/bigmuddy-network-telemetry-proto/proto_go"
	pdt "github.com/cisco/bigmuddy-network-telemetry-proto/proto_go/old/telemetry"
        ...
)

Go generate could do this for us, but not sure if it something we want to support.