This was likely broken since #3313 and leads to IOx reporting `UKNOWN`
instead of a proper GIT revision. Having the latter one available can be
very useful for debugging a binary or if you look through log files (we
print the IOx version and revision during server startup).
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
This adds a simple Dockerfile for anyone to just `docker build .` and
get a Docker image. This Dockerfile is optimized for human consumption,
not for build performance.