Shortcut to avoid error attempting to load 'null.js'

- Reference new type alias
- Remove inaccurate information

Note that none of the built in formatters use this value, but the tests + docs refer to it.

The runtime and syntax bundles are now output as ES modules. This allows use of dynamic import `import()`.  Which means this bundle can (partially) match the existing stylelint API where the `customSyntax` option accepts a "path to a JS file exporting a PostCSS-compatible syntax".

Ref: https://stylelint.io/user-guide/usage/options#customsyntax

This means syntax loading can be handled externally from stylelint. This requires overloading the customSyntax option to also accept an object, but should make things a bit more flexible. It also avoids the weirdness of having an (ignored) ESM `import()` in a CommonJS module.

This matches other parts of stylelint more closely, and leaves the option of exporting additional methods in future.

This enables non-standard syntaxes to be passed into the browser bundle.

Manually replace `require.cache` calls with an empty object in the dist/ bundles.

Update package-lock.json

# By Mike Allanson (6) and others
# Via GitHub
* master:
  Bump got from 11.2.0 to 11.3.0 (#4825)
  Export an object from the CSS-in-JS syntax (#4824)
  Add type `Formatter` for formatter functions (#4823)
  Update CHANGELOG.md
  Fix false positives for namespaced variables in property-no-unknown (#4803)
  Update CHANGELOG.md
  Fix TypeError for inline comments and autofix for sugarss in max-empty-lines (#4821)
  Create new 'lintPostcssResult' module (#4819)
  13.6.0
  Update deps
  Prepare 13.6.0
  Update CHANGELOG.md

# By jeddy3 (4) and others
# Via GitHub
* master:
  Create new 'prepareReturnValue' module (#4832)
  13.6.1
  Scope eslint disable
  Prepare 13.6.1
  Update deps
  Update CHANGELOG.md
  Fix false positives for idents within ::part pseudo-elements in selector-type-no-unknown (#4828)
  Bump np from 6.2.3 to 6.2.4 (#4830)

# By Mike Allanson (2) and others
* master:
  Fix changelog formatting
  A small refactor (#4837)
  Update CHANGELOG.md
  Add ignoreContextFunctionalPseudoClasses to selector-max-id (#4835)

This means no config is needed in `package.json`

# By Richard Hallows (4) and others
# Via GitHub
* master:
  Create codeql analysis workflow (#4850)
  Update CHANGELOG.md
  Add support for descriptions in stylelint command comments (#4848)
  Update CHANGELOG.md
  Add *-allowed-list/*-disallowed-list/*-required-list names for *-whitelist/*-blacklist/*-requirelist rules (#4845)
  Update CHANGELOG.md
  Add syntax object acceptance to customSyntax option (#4839)
  Bump typescript from 3.9.5 to 3.9.6 (#4853)
  Add ignoreComments[] to comment-empty-line-before (#4841)
  Bump autoprefixer from 9.8.0 to 9.8.2 (#4838)

* master:
  Update CHANGELOG.md
  Fix false negatives for where, is, nth-child and nth-last-child in selector-max-* (except selector-max-type) (#4842)
  Bump @types/lodash from 4.14.155 to 4.14.157 (#4869)
  Remove `postcss-reporter` package (#4858)
  Bump lodash from 4.17.15 to 4.17.19 (#4864)
  Replace 3rd-party type definitions (#4857)

* master: (34 commits)
  Update CHANGELOG.md
  Fix double-slash disable comments when followed by another comment (#4913)
  Update CHANGELOG.md (#4916)
  13.7.0
  Prepare 13.7.0
  Prepare changelog
  Update dependencies
  Update CHANGELOG.md
  Deprecate *-blacklist/*-requirelist/*-whitelist (#4892)
  Fix some path / glob problems (#4867)
  Update CHANGELOG.md
  Add a reportDescriptionlessDisables flag (#4907)
  Fix CHANGELOG.md format via Prettier (#4910)
  Fix callbacks in tests (#4903)
  Update CHANGELOG.md
  Fix false positives for trailing combinator in selector-combinator-space-after (#4878)
  Add coc-stylelint (#4901)
  Update CHANGELOG.md
  Add support for *.cjs config files (#4905)
  Add a reportDisables secondary option (#4897)
  ...

* master: (46 commits)
  Update CHANGELOG.md
  Add ignoreAtRules to property-no-unknown (#4965)
  Bump eslint from 7.11.0 to 7.12.1 (#5017)
  Bump typescript from 4.0.3 to 4.0.5 (#5016)
  Bump lint-staged from 10.4.0 to 10.5.1 (#5014)
  Bump remark-cli from 8.0.1 to 9.0.0 (#4996)
  Bump jest-circus from 26.5.3 to 26.6.1 (#5009)
  Bump got from 11.7.0 to 11.8.0 (#5007)
  Bump jest from 26.5.3 to 26.6.1 (#5008)
  Refactor formatter tests (#4988)
  Fix `isStandardSyntaxDeclaration.test.js` that use callbacks (#4972)
  Update CHANGELOG.md
  Add "comment-pattern" rule (#4962)
  Update CHANGELOG.md
  Show the pattern in "*-pattern" rule messages (#4975)
  Enable ESLint `no-shadow` and add disable comments (#4986)
  Report disables in the same manner as lints (#4973)
  Update dependencies (#4982)
  Fix some tests that use callbacks (#4970)
  Use own vendor utility instead of PostCSS (#4942) (#4963)
  ...