Add docker image for running debos

Docker allows for an easy way to get a reproducible build environment,
add a docker file containing debos which can be used for image builds.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D7243