[docker-compose] One image to bind them all
As pointed by @vlorentz yersteday in a f2f discussion, building the whole set of docker images associated to each swh service takes too much time.
Moreover there is a lot of duplicated instructions in the service dockerfiles. This calls for factorization in order to ease future maintenance of that environment.
So, in order to speed up the docker-compose build process but also to remove duplicated instructions in dockerfiles, prefer to use a single docker image containing the full swh stack. Each swh service will run upon it while their specific configuration (for instance entrypoint) will be picked from the docker-compose.yml file.
Migrated from D1238 (view on Phabricator)