refactor: docker inspection refactor (ee7 review)

[ee7]

Suggestions for #266.

I'll do this via PR in this case because:

• I review locally anyway
• I make the changes locally anyway
• I write the commit messages anyway
• It ensures that commits in the PR contain the review comments
• I don't have to copy changes and comments to the PR via the web UI, or use a tool that supports applying local changes to a PR via the GitHub API
• I can check that the changes compile, and make fewer broken suggestions

See commit messages.

---

To-do:

• [ ] Finish reviewing https://github.com/crashappsec/chalk/pull/266/commits/84a01736f5b9246b8fd23e0d6a8f3835019d7c52

[miki725]

some feedback is addressed in https://github.com/crashappsec/chalk/pull/282