Allow ESM imports of the data

[queengooborg]

This PR fixes #15916 and allows ESM users to directly import BCD by performing two things:

• Remove the redundant index.js to import the data (NodeJS has always been able to require() JSON) and export data.json by default
• Add a wrapper for NodeJS v12-v14 ESM, since they do not support import assertions, which can be imported via import bcd from "@mdn/browser-compat-data/NodeWrapper";

I tested to make sure this approach works using require() in NodeJS v18, v16, v14, v12, and even v4; and using import in NodeJS v18, v16, v14, and v12, all successfully importing BCD.

This is marked as a semver-major-bump because exports is defined which may break existing setups (i.e. if users are already trying to import data.json directly).

This closes #15775, which also offers ESM import capability, but at the cost of double the bundle size.

[github-actions]

This pull request has merge conflicts that must be resolved before we can merge this.

[github-actions]

This pull request has merge conflicts that must be resolved before we can merge this.

[github-actions]

This pull request has merge conflicts that must be resolved before we can merge this.

[caugner]

LGTM, just some bike-shedding