Start of Eleventy v4: Extract Core.js, Removes ndjson, Fork gray-matter, Removes slug filter, Adds @11ty/client package and publish workflow

[zachleat]

• Fixes Extract core (no dev server, no chokidar) class from Eleventy.js #3836 (extracts reduced core for use without watch/serve, useful for serverless, etc)
• Fixes Remove --to=ndjson feature #3382 (removes ndjson feature)
• Fixes Fork gray-matter to eliminate eval usage (and more) #3892 Swaps to use @11ty/gray-matter fork of gray-matter for reasons explained https://github.com/11ty/gray-matter#11tygray-matter
• Removes slug Filter (deprecated since v1.0.0), Remove slug filter (deprecated in v1) #3893
• Adds --to=fs:templates CLI option (and to write to file system but skips over passthrough copy. Also adds Eleventy#write("templates") and Eleventy#write("copy")
• Adds support for sub-package @11ty/client for client use:
  • import { Eleventy } from "@11ty/client" (reduced core)
  • import { Eleventy } from "@11ty/client/eleventy"
  • import { Liquid } from "@11ty/client/liquid"
  • import { Nunjucks } from "@11ty/client/njk"
  • import { Markdown } from "@11ty/client/md"
• Adds Vitest for client browser-based automated test suite.
• Adds eleventyConfig.addEngine method to directly expose TemplateEngine additions
• Prefers import-module-string in some cases over node-retrieve-modules More info: https://www.zachleat.com/web/dynamic-import/
• Adds .core.js and .core.min.js adapters for removal of some optional features for reduced client bundle size.
• Adds release.sh script to automate release of core and client packages together.

TODO: Still learning towards removing the client bundles from this package and moving to a separate package (to keep package size small)

Client Bundle Features

Feature	@11ty/client/eleventy	@11ty/client
YAML Front Matter	Yes	Yes
Liquid Engine	Use @11ty/client/liquid	Use @11ty/client/liquid
Nunjucks Engine	Use @11ty/client/njk	Use @11ty/client/njk
Markdown Engine	Use @11ty/client/md	Use @11ty/client/md
JavaScript Engine	Yes	Yes
HTML Engine	Yes	Yes
Arbitrary JavaScript Front Matter	Yes (via import-module-string)	Yes-ish (low-fidelity data: requires export)
Legacy js JavaScript object Front Matter	Yes	Yes
Configuration support	Yes	Yes
slugify Filter	Yes	No (error)
url Filter	Yes	No (error)
get*CollectionItem filters	Yes	No (error)
inputPathToUrl Filter	Yes	No (error)
HTML Transformer	Yes	No (noop)
Bundle Plugin	Yes	No (error)
Relative Copy Plugin	Yes	No
IdAttribute Plugin	Yes	No
HtmlBase Plugin	Yes	No
InputPathToUrl Plugin	Yes	No
Render Plugin	Yes	No
I18nPlugin	Use @11ty/client/i18n	Use @11ty/client/i18n
Custom Engine Config API	Yes	Yes
Parse JavaScript Dependencies (for watch)	No (error)	No (error)
Luxon date parsing fromISOtoDateUTC removed in #3587	N/A	N/A
ISO8601 String Date parsing	Yes	Yes
UserConfig resolvePlugin	Yes	No (error)
Node.js ESM Cache Buster	No (noop)	No (noop)
Glob Matching (collections, input globs, passthrough copy)	Yes	No (error)
Dynamic import()	Yes (via import-module-string)	No (Possibly later)
Config versionCheck	Yes (costs ~38KB)	No (always returns true)
Content Date Git First Added or Last Update	No (error)	No (error)