Remove deprecated CommonJS Node.js API

[ybiquitous]

When releasing 16.0.0, we announced we would remove the CommonJS Node.js API in the next major version. See the migration guide:

stylelint/docs/migration-guide/to-16.md

Lines 5 to 7 in da7ce21

	We've migrated our source code to [ECMAScript modules](https://nodejs.org/docs/latest/api/esm.html) (ESM) — a year-long effort to allow ESM plugins, custom syntaxes and formatters, and a step towards updating our pure ESM dependencies.
	To give the community time to migrate to ESM, we'll publish a hybrid package to support the (now deprecated) CommonJS Node.js API until our next major release.

Also, we must drop the support for CommonJS plugins because Stylelint plugins written in CommonJS cannot import pure ESM Stylelint modules (e.g., require('stylelint') will be errored).

stylelint/lib/augmentConfig.mjs

Lines 323 to 328 in da7ce21

	// NOTE: This '.cjs' check is limited. Some CommonJS plugins may have the '.js' extension.
	if (!quietDeprecationWarnings && pluginLookup.endsWith('.cjs')) {
	console.warn(
	`CommonJS plugins are deprecated ("${pluginLookup}"). See https://stylelint.io/migration-guide/to-16`,
	);
	}

By doing this, we will be able to achieve:

• Remove .cjs files (the package size reduces)
• Remove the build workflow via Rollup
• Make the codebase pure ESM (maybe with .mjs → .js change?)
• Bump outdated pure ESM dependencies

[ybiquitous]

@jeddy3 If you have additional info or find some mistakes, please feel free to edit the issue description.

[jeddy3]

All looks good to me! I've created a new label for things that are agreed on but held for a time.

When the time is right, we'll switch to status: ready to implement.

[ybiquitous]

Yeah, it will be a while (maybe 1 year later?)

[ybiquitous]

I've just opened an issue #7397, too.

[jeddy3]

Yeah, it will be a while (maybe 1 year later?)

I agree that it may be a while. We can check every few months to see how far along the JavaScript and Stylelint communities are in migrating to ESM, rather than put a fixed time on it.