feat: provide image with nginx

[walidmujahid]

[ehuelsmann]

I'm wondering if we should add a script in all branches which builds the image(s) in the branch. That way, I don't have to teach the release infrastructure about the difference between the 1.12 branch and prior branches (the 1.12 branch will need 2 images built (times 3 architectures) -- earlier branches only had 1 (sometimes without the other architectures, even))

[ehuelsmann]

@walidmujahid hi! do you have an opinion on the points above?

[ehuelsmann]

@neilt @freelock I think including the proxy in the LedgerSMB image is a much better solution, because in the deployments where I actually deployed the proxy, I had to create a shared volume, which needs to be deleted before upgrading, because the volume is duplicated into the proxy on creation, not replicated (and thus updated on update).

Also, do you have an opinion on switching away to use a unix socket to communicate between ledgersmb and nginx?

[neilt]

Should we consider adding Postgres to this image with Nginx? This would create an excellent demo docker image that could be loaded and run from Docker Desktop. The result would require no command line usage and could easily be tried by potential new users.

[ehuelsmann]

@walidmujahid Thanks for the contribution! It's now merged and will be used when creating 1.13 releases!