Partially extracted from #7547
Updates protobuf to the most recent in the 1.3.x series, and updates
golang.org/x/sys to a7d97aace0b0 because of https://github.com/shirou/gopsutil/issues/853
prevents updating to a more recent version.
This breaking change in x/sys also prevents us from getting a newer
version of x/net. In the future, if gopsutil is not patched, we may want to run a fork version of
gopsutil so that we can update both x/net and x/sys.
* Vendor updates for gRPC and xDS server
* xDS server implementation for serving Envoy as a Connect proxy
* Address initial review comments
* consistent envoy package aliases; typos fixed; override TLS and authz for custom listeners
* Moar Typos
* Moar typos
Daniel Nephin