Add docker storage driver to fingerprint

[passcod]

Proposal

Add the docker daemon storage driver setting to Nomad's fingerprinting (so it can be constrained on).

Use-cases

Docker-in-docker behaves badly (eg moby/moby#9939) when the storage driver is set to btrfs.

Attempted Solutions

We set a meta attribute to the configured storage driver and constrain based on that. It works okay, but requires our intervention obviously. It would be ideal to have it directly pulled by Nomad. However, this is more of a "nice to have".

[tgross]

Hi @passcod! This is the sort of thing we want to be able to enable with the work described #9063. This issue describes a specific use case that's slightly different, so I'm going to keep this issue open and get it into the roadmap for when we look at #9063.