extract-files 9.0.0 on Node.js NPM

Major

Updated Node.js support to ^10.17.0 || ^12.0.0 || >= 13.7.0.
Updated dev dependencies, some of which require newer Node.js versions than previously supported.
Renamed the lib directory to public; existing deep import or require paths must be updated.
Removed the package module field.

Removed Node.js v13 and added v14 to the versions tested in GitHub Actions.
Simplified the GitHub Actions CI config with the npm install-test command.
Improved JSDoc code examples.
Updated EditorConfig.
No longer transpile tests with Babel, or test ESM.
Simplified the Babel config and scripts, ensuring .js files are parsed as scripts.
Removed unnecessary .js file extensions from require paths.
Documented all the ways to import and require the public API.
Tweaked the readme setup instructions.