Use native mkdirSync instead of 'mkdirp' package

[Krinkle]

Description

In Node.js 10 and later, recursive mkdir is available in core. No longer needs the mkdirp package.
https://nodejs.org/docs/latest-v10.x/api/fs.html#fs_fs_mkdirsync_path_options

Before Merge Checklist

• Source branch in your fork has meaningful name (not master)
• JavaScript implementation
• Python implementation (NA if HTML beautifier)
• Added Tests to data file(s)
• Added command-line option(s)
• README.md documents new feature/option(s)

Ref 11ty/eleventy#1375.

[bitwiseman]

Thanks!

We just took node 8 out of the CI run, but as far as I know the library still runs on versions back to node 6.

Is there a strong reason to make this move?

If we go this route we'll need to release a version that includes an engines section in the package.json first, with Node 10 as the minimum version.

https://stackoverflow.com/questions/29349684/how-can-i-specify-the-required-node-js-version-in-package-json

Would you might create a PR that first step? And then update this PR to be the second step?

[Krinkle]

@bitwiseman The main motivation for this is to reduce the size of the dependency graph for downstream users of js-beautify, thus requiring fewer packages to be audited and trusted.

As Node 8 is beyond its EOL date, I assumed requiring Node 10 for new releases would be uncontroversial (https://github.com/nodejs/Release). I'll see about making those PRs!

[bitwiseman]

@Krinkle
You'd be surprised about what is controversial for this library.
I totally agree with reducing the dependency graph. We just tend to move really slowly on breaking changes like this.

[bitwiseman]

Waiting for publishing of some additional v1.13.x releases. Will merge for 1.14.0.

[Krinkle]

You'd be surprised about what is controversial for this library.

To clarify, I didn't mean that it should be uncontroversial, just that figured there's a good chance that it might be, given it was no longer tested for (and EOL). If correct, then this change can help improve something downstream. But, if support is meant to remain, that's totally fine with me! I'm just going through the large tree I'm currently auditing, simplifying code where possible and sometimes proposing to remove potentially obsolete fallbacks.

[Krinkle]

Merge conflict resolved.