package: Added script to build a debian package locally

This use docker, so it should be OS/distro agnostic as long as you
have docker installed (or podman, untested though).

Bug: T316228
Change-Id: I29e73bd0cd4b681c251b4716e6a0ea0c66281eaf
Signed-off-by: David Caro <dcaro@wikimedia.org>