artifact: implement findHomeDir helper as specified

[chrisroberts]

Description

This makes a couple small changes to the findHomeDir helper function to properly match the described behavior. It will attempt to use os.UserHomeDir first, and if no path can be discovered, it will return /dev/null.

Testing & Reproduction steps

Links

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Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

[tgross]

I don't think we want this: the os.UserHomeDir function only looks at the environment, whereas homedir.Dir looks at the environment and then has some platform-specific fallback behavior. We're calling homedir.Dir() anyways, so I don't think this gets us anything and it's the docstring of the function that should be fixed instead.

[chrisroberts]

That's fair! I've updated the docstring and kept the path change.

[tgross]

LGTM!