Avoid 'create' when entering non-existent container

[findurance]

How to avoid creating a container, when distrobox enter command executed, but the container does not exist?

The default behavior now seems to be creating a new container according to distrobox.conf, which is actually rather clumsy as a default action.

In that regard, there should be a --create-if-not-existing -type of flag instead to trigger the creation in this case. Especially since there seems to be no obvious way to check if a particular container exists.

Now the default behavior induces creation of unnecessary containers, when for example typoing a container name.