Volume mounts

[raphaeltm]

I know that it would be somewhat anathema to many aspects of Defang's philosophy, but I think we should support volume mounts for service. I think it's okay if we have some caveats around it.

Let's say someone wants to run a database like EdgeDB, using their Docker image and their compose example. It strikes me as really unfortunate that at the moment:

• we don't have a safe way to run this because there's no way to persist the state
• there are loads of compose examples in the wild for interesting databases and stateful services that Defang users can't just download and defang compose up because they use volume mounts to persist data

I think it should be fine to allow this with warnings/caveats/explicit instructions that the user understands the downsides of running such services.