Reformat files: add package.json script to reformat css

While at it, rename Stylelint config to `.stylelintrc.json` to get it automatically formatted by Prettier as well.

See https://stylelint.io/user-guide/configuration/#loading-the-configuration-object for more about config file names.

Run reformat-files:* in series, not in parallel

Always happy exit

reorganise

package.json

@@ -271,7 +271,9 @@
 		"prestart": "npx check-node-version --package && npm run -s install-if-deps-outdated && node bin/welcome.js",
 		"start": "npm run -s build",
 		"poststart": "run-p -s start-build-if-web start-build-if-desktop build-packages:watch",
-		"reformat-files": "./node_modules/.bin/prettier --ignore-path .eslintignore --write \"**/*.{js,jsx,json,ts,tsx}\"",
+		"reformat-files": "run-p -c reformat-files:*",
+		"reformat-files:js": "./node_modules/.bin/prettier --ignore-path .eslintignore --write \"**/*.{js,jsx,json,ts,tsx}\"",
+		"reformat-files:css": "npm run -s lint:css -- --fix || exit 0",
 		"start-build-fallback": "cross-env-shell BROWSERSLIST_ENV=defaults NODE_PATH=$NODE_PATH:server:client:. node $NODE_ARGS --max_old_space_size=8192 build/bundle.js",
 		"start-build-evergreen": "cross-env-shell BROWSERSLIST_ENV=evergreen NODE_PATH=$NODE_PATH:server:client:. node $NODE_ARGS --max_old_space_size=8192 build/bundle.js",
 		"start-build-if-desktop": "node -e \"(process.env.CALYPSO_ENV === 'desktop' || process.env.CALYPSO_ENV === 'desktop-development') && process.exit(1)\" || npm run start-build-fallback",