* Protobuf Modernization
Remove direct usage of golang/protobuf in favor of google.golang.org/protobuf
Marshallers (protobuf and json) needed some changes to account for different APIs.
Moved to using the google.golang.org/protobuf/types/known/* for the well known types including replacing some custom Struct manipulation with whats available in the structpb well known type package.
This also updates our devtools script to install protoc-gen-go from the right location so that files it generates conform to the correct interfaces.
* Fix go-mod-tidy make target to work on all modules
Our original intention was for projects to consume and generate their
own Go code for these protobuf packages using Buf. While this is still
the best route for many projects, it causes some headaches when using
a library (e.g. consul-server-connection-manager) that pulls in the
same protobuf package as your project, as Go's protobuf implementation
only allows for a package/namespace to be registered once.
In such cases, projects can depend on this Go module instead, as a
single place where these protobuf packages are registered.
Matt Keeler
Daniel Upton