Check for missing docker dir

[BretFisher]

Docker v23 no longer creates the /etc/docker/ directory, so we need to create it and don't error if it already exists (for older versions).

[thaJeztah]

LGTM

[thaJeztah]

We were discussing this, and the /etc/docker directory was previously created as a side-effect of a legacy functionality for schema 2 v1 images ("libtrust"), which created a key.json in this path.

In general, I think this is the correct fix, as this directory is not guaranteed to be present (it's an optional path to store config files). That said, we'll make a change in the .deb and .rpm packages to automatically create an empty directory on installation;

• [master] deb, rpm: add /etc/docker directory docker/docker-ce-packaging#841
• [23.0 backport] deb, rpm: add /etc/docker directory docker/docker-ce-packaging#842

[jpetazzo]

Good catch, thank you! <3