distrobox should be created if containter does not exist not if folder does not exists

[kapi117]

currently script is checking if folder exists. better option would be to check if container itself exists - current solution leads to issues if container creation fails

[rayferric]

The reason we look at whether the folder exists instead of querying Docker is that when I originally developed the ./distrobox script, I observed that the queries were noticeably slower which negatively impacted user experience.

However, now that I look into it, distrobox ls command is not that slow and could be used. Even better, we could directly run docker/podman container ls -a, which appears to answer instantaneously.