Add proto for analysis messages

[zerobfd]

See https://docs.google.com/document/d/1lCnDBVzRzkr22BWjzPtGk6EK6EvGOnVIe2qBpaiQ3SM/ for more context and discussion around the change.

I split the struct up a bit differently than the doc to make things (hopefully) more clear and make the developer UX a bit easier.

[zerobfd]

/test build_api

[geeknoid]

There's a few things missing here.

#1. This new proto isn't being built. It needs to be built and linted. So it needs to be integrated into the make system.

#2. If you want this content to be documented on istio.io, then you need to add the needed voodoo in the makefile in order to produce a .pb.html file. If you do not intend to document this on istio.io, then you should remove the $ directives in the comments at the top of the file, since those are only relevant for the doc publishing process.

#3. Since I believe this proto will be used to describe status in Istio CRDs, then this probably will need to be integrated with the build of the .json files that described our schema to the API server. And will probably need to be integrated with the client-go libraries in order to enable programmatic access to the status state. @jasonwzm can help with the JSON stuff, @richardwxn can help with the client-go stuff.

[zerobfd]

/retest

[zerobfd]

/retest

[jasonwzm]

@zerobfd Can you rebase again to make gencheck work?

[louiscryan]

can you clarify the meaning of 'path for resources' ?

[zerobfd]

I intended this to mean the "kind/namespace/resource" construction which identifies a resource, but then someone told me that wasn't a path, it was a qualified resource name. Although when I google around I don't see anything about that--is there a concept of a resource ID somewhere that I can link to?