Require stylelint v14 for stylelint config and scripts (#38091)

* Update stylelint config to require v14

* Bump stylelint dependency for scripts

* Update package-lock.json

* Ignore SCSS test files for stylelint check

* Fix minor SCSS lint issues

* Use the correct preset for linting SCSS files

* Disable stylelint rules until these are fixed

* Remove duplicate PostCSS dependencies

* Update tests for updated rules

* Add PR to changelog

.stylelintignore

@@ -0,0 +1 @@
+packages/stylelint-config/test

.stylelintrc.json

@@ -1,5 +1,5 @@
 {
-	"extends": "@wordpress/stylelint-config",
+	"extends": "@wordpress/stylelint-config/scss",
 	"rules": {
 		"at-rule-empty-line-before": null,
 		"at-rule-no-unknown": null,
@@ -9,6 +9,17 @@
 		"no-descending-specificity": null,
 		"rule-empty-line-before": null,
 		"selector-class-pattern": null,
-		"value-keyword-case": null
+		"value-keyword-case": null,
+		"scss/operator-no-unspaced": null,
+		"scss/selector-no-redundant-nesting-selector": null,
+		"scss/at-import-partial-extension": null,
+		"scss/no-global-function-names": null,
+		"scss/comment-no-empty": null,
+		"scss/at-extend-no-missing-placeholder": null,
+		"scss/operator-no-newline-after": null,
+		"scss/at-if-closing-brace-newline-after": null,
+		"scss/at-else-empty-line-before": null,
+		"scss/at-if-closing-brace-space-after": null,
+		"no-invalid-position-at-import-rule": null
 	}
 }

docs/contributors/folder-structure.md

@@ -15,6 +15,7 @@ The following snippet explains how the Gutenberg repository is structured omitti
     ├── .jshintignore
     ├── .eslintignore
     ├── .prettierrc.js
+    ├── .stylelintignore
     ├── .stylelintrc.json
     ├── .markdownlintignore
     ├── .npmpackagejsonlintrc.json