v3: Bundle postcss-load-config v4 with the standalone CLI (#19042)

Unfortunately, it’s not possible to intercept the `await import(…)` used
by newer versions. This means the Standalone CLI will not be able to
load ESM postcss config files. You still will using the npm package and
newer versions of Node.js.

Author: thecrypticace

standalone-cli/package-lock.json

@@ -23,6 +23,7 @@
     "jest": "^27.5.1",
     "move-file-cli": "^3.0.0",
     "pkg": "^5.8.1",
+    "postcss-load-config": "^4.0.2",
     "rimraf": "^3.0.2",
     "tailwindcss": "file:.."
   },

standalone-cli/package.json

@@ -18,6 +18,11 @@ let localModules = {
   },
   '@tailwindcss/typography': require('@tailwindcss/typography'),
 
+  // This force-loads the v4 version instead of the v6 one at the repo root
+  'postcss-load-config': require('postcss-load-config'),
+  'postcss-load-config/src/options': require('postcss-load-config/src/options'),
+  'postcss-load-config/src/plugins': require('postcss-load-config/src/plugins'),
+
   // These are present to allow them to be specified in the PostCSS config file
   autoprefixer: require('autoprefixer'),
   tailwindcss: require('tailwindcss'),