Stable release of Go generated protos

Anyone writing a Go application that wishes to use Envoy protos will need a stable release of this repo. In case you are not aware, proto definitions cannot be generated independently by libraries, since multiple versions of the generated code for a single message that make their way into the same binary will cause a panic at init time. And without a stability guarantee, use of this repo as the official source of the protos is risky. Please create a stable v1.x release of this repo ASAP. Thank you.

Related to https://github.com/cncf/udpa/issues/42 and https://github.com/envoyproxy/go-control-plane/issues/391.

cc @htuch

Start by reviewing this issue's comment thread and the related discussions in cncf/udpa#42 and envoyproxy/go-control-plane#391. The requested outcome is a stable v1.x release of this repository for applications using the Envoy protos; the payload names no files, tests, or release entry point.

Written by the indexing model from the issue text.