Consider Switching to a ESM-only package

[nicholasio]

Is your enhancement related to a problem? Please describe.

The Node.js ecosystem is evolving and there's a push for shipping ESM-only packages.

Given we're already supporting only Node.js >= 16 it should be relatively safe to switch 10up-toolkit from commonjs to ESM Modules in the next major version.

There are several deps we're relying on where new versions only ships ESM and therefore we cannot update them yet.

Since this is mostly a CLI tool it won't force users to switch their projects to ESM. Additionally, we can still export the configs files via commonjs so that users can extend the config as usual without having to switch to ESM modules.

Designs

No response

Describe alternatives you've considered

No response

Code of Conduct

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