add support for building debian/ubuntu based images

[obnoxxx]

No description provided.

[phlogistonjohn]

While I am not strictly opposed to this idea I think that supporting lots of different base images has costs and we should be judicious about what bases we use and how many images we end up supplying.
To justify having these I'd want to consider:

• user demand: is anyone outside the team asking for these
• features: is there something the ubuntu or debian builds of samba do that the current images can not or do not?
• team expertise: it would be best if someone familiar with those distro ecosystems helped maintain these variants
• testing: either we test and make use of these variants or we should have some way of expressing that some images are "1st tier" vs "best effort" or something like that
• distribution and documentation: how do users know the variants exist and how should they acquire them. How should users know which ones are best to use