Server version / metadata api

[devinrsmith]

It would be nice if the web UI could report on the server's version, or other metadata. Some of this metadata is available as labels on the docker images, but it should likely be part of the server gRPC api.

[jcferretti]

I have a need for something similar from the python wrapping code for C++ using cython. We are borrowing heavily from the code pyarrow uses, and in their build process they capture a version string for inclusion in the packaged library. I discussed briefly with Devin the mechanism that they use, which pivots on git describe --tags. That won't work as is for us right now, given how we are currently doing release branching and tagging, but thinking around that could be part of a recipe here, so sharing it.