Merge pull request #3611 from Automattic/add/stylelint

Adds style linting like we do it in Gutenberg

.stylelintrc.json

@@ -0,0 +1,3 @@
+{
+    "extends": [ "@wordpress/stylelint-config/scss" ]
+}

package.json

@@ -14,15 +14,23 @@
 	},
 	"devDependencies": {
 		"@wordpress/prettier-config": "^1.0.1",
+		"@wordpress/scripts": "^14.0.1",
+		"@wordpress/stylelint-config": "^19.0.1",
 		"chokidar-cli": "^2.1.0",
 		"husky": "^4.3.0",
+		"lint-staged": "^10.5.4",
 		"lodash": "^4.17.20"
 	},
 	"husky": {
 		"hooks": {
-			"pre-commit": "node pre-commit-hook.js"
+			"pre-commit": "lint-staged && node pre-commit-hook.js"
 		}
 	},
+	"lint-staged": {
+		"*.{css,scss}": [
+			"wp-scripts lint-style --fix="
+		]
+	},
 	"dependencies": {
 		"wp-prettier": "^2.0.5"
 	}