What

Introduce dockerfiles for Debian users.

Why

This is quite handy to have a dockerfile per OS so that one can run tezt-cloud scenarios without any configuration.

How

Copy/Pasted from saroupille.Dockerfile and removed the binaries.

Manually testing the MR

If you are a Debian-like user:

dune exec tezt/tests/cloud/main.exe -- cloud dal -v --log-file /tmp/log --producers 1 --dockerfile-alias debian

And observe the scenario runs correctly. If you are not a Debian-like user, then trust the code 😄