Allow using the compiler as an ESM module

[Pierstoval]

This PR provides a first solution to #4806, allowing the compiler to be built to ESM

[Pierstoval]

Good! Waiting for core team approval 👍

[afaur]

Bump, I notice there are some lint errors, but if that's an issue can we let @Pierstoval know or merge this as is? (could do a fixup PR later if an issue)

[Pierstoval]

I just rebased on master, let's see if these errors are still here, and if not, maybe I'll be able to fix them? 😉

[afaur]

I was incorrect about the lint issues.

• It says Unchanged files with check annotations which indicates they are not in your changes.

[antony]

You can ignore the lint issues, they're because we added loose linting rules and tried not to break the existing collection of PRs. It's on my list to fix all of the lint issues.

[antony]

This looks fine, it publishes a completely separate mjs version of the compiler.

[Pierstoval]

Thanks for merging 👍