doc: Extend esm examples, document and lint import forms for process + Buffer

[guybedford]

This updates the use of esm examples in the documentation to cover more core modules while encouraging the use of Buffer and process imports / requires where possible, instead of saying that this is unnecessary. It does not deprecate or say that the global forms are deprecated though.

Summary:

• Split examples into ESM / CJS sections for: async_context, async_hooks, cluster, dgram, diagnostics_channel (as far as I could go in one sitting!)
• Update both process and buffer to always show the import form in usage examples, noting this is encouraged but not required.
• In addition, destructured import forms are given preference where suitable.
• Add an eslint rule for the docs to not include process / Buffer without being imported and fix all cases.

@nodejs/modules

[bmeck]

It might make sense to modify

node/.eslintrc.js

Lines 65 to 101 in f4609bd

	files: ['**/*.md/*.cjs', '**/*.md/*.js'],
	parserOptions: {
	sourceType: 'script',
	ecmaFeatures: { impliedStrict: true }
	},
	rules: { strict: 'off' },
	},
	{
	files: [
	'**/*.md/*.mjs',
	'doc/api/esm.md/*.js',
	'doc/api/packages.md/*.js',
	],
	parserOptions: { sourceType: 'module' },
	rules: { 'no-restricted-globals': [
	'error',
	{
	name: '__filename',
	message: 'Use import.meta.url instead',
	},
	{
	name: '__dirname',
	message: 'Not available in ESM',
	},
	{
	name: 'exports',
	message: 'Not available in ESM',
	},
	{
	name: 'module',
	message: 'Not available in ESM',
	},
	{
	name: 'require',
	message: 'Use import instead',
	},
	] },

and add a no-restricted globals for Buffer and process.

[guybedford]

Thanks, I've gone ahead and added the lint rule for Buffer and process and fixed up all cases.

I've also updated the process docs to use destructured import forms wherever possible as well eg import { cwd } from 'process'.

[aduh95]

I subjectively prefer path.join rather than simply join, feel free to disregard if you disagree.

Suggested change

	dlopen(module, join(__dirname, 'local.node'), constants.dlopen.RTLD_NOW);
	dlopen(module, path.join(__dirname, 'local.node'), constants.dlopen.RTLD_NOW);

[guybedford]

I did go quite agressive on the destructured imports, down to leaving out cases like "on". I understand some of these get tricky, but want to try and encourage this as much as possible for tree-shaking style optimizations. In theory leaving out the member expression access is more performant as well although it's a micro-optimization for sure. Will leave this in unless anyone wants to push back further.

Addressed

[bmeck]

LGTM, docs only change, would want to do some styling work to agree how to reduce noise viewing overall size of docs in a different PR.

[guybedford]

Landed in f4d0a6a.

[aduh95]

@guybedford the lint rule only targets ESM syntax, is that on purpose? For info there are 135 occurrences of Buffer and process used as globals in CJS code snippets.