Setup workstation testing

[mvgijssel]

Now that workstation provisioning is done with Pyinfra (#96) there need to be automated tests to verify that everything keeps working as expected. https://github.com/inspec/inspec looks like the most mature framework to use for infrastructure testing and is also already used for the hypervisor testing.

For similar reasons as outlined here #97 let's move these tests into a docker container so we're not dependent on host (macOS) dependencies when installing/compiling Ruby dependencies.

TODO tests

• expect fig docter to return exit status 0
• expect python binary to come from asdf (and not built-in macOS)
• ensure we are using git version > 2.34 for git commit signing https://developer.1password.com/docs/ssh/git-commit-signing
• ensure /etc/ssh/sshd_config contains a line only allowing docker-for-mac vm access to macOS