Add recursive arg to mkdir

[JordanMartinez]

Description of the change

Enables a variant of mkdir that works when multiple directories in the path don't exist.

https://nodejs.org/api/fs.html#fspromisesmkdirpath-options

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Checklist:

• Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• Linked any existing issues or proposals that this pull request should close
• Updated or added relevant documentation
• Added a test for the contribution (if applicable)

[garyb]

mkdir' is exported too, so this is a breaking change in its current form, is that the way we want to go?

[JordanMartinez]

I can refactor this to use a different FFI call rather than going through mkdir'. When we do breaking changes in the future, we can merge the two then.