Support deploying without a Dockerfile

[nckrtl]

It would be nice to be able to deploy spin projects that do not contain a Dockerfile. For example I have deployed a spin project with just containing a traefik service, allowing to deploy multiple web projects on a single server that use the same Traefik instance.

The +e/-e is needed to make sure the deploy script doesnt exit when no dockerfile is found. This happens on Mac when ls is not returning any results. There might be a better way around this, I'm open for alternatives.