Added stylelint

Summary:
Ref T2889

Test Plan: arc lint --everything | grep .css

Reviewers: FilipI

Reviewed By: FilipI

Subscribers: FilipI, kuba-orlik, jenkins-user

Maniphest Tasks: T2889

Differential Revision: https://hub.sealcode.org/D1553

.arclint

@@ -1,3 +1,11 @@
 {
-	"linters": {}
+  "linters": {
+    "stylelint": {
+      "type": "script-and-regex",
+      "script-and-regex.script": "2>&1 npx stylelint",
+      "script-and-regex.regex": "/^(?P<message>.*)$/m",
+      "include": ["(\\.css$)"],
+      "exclude": []
+    }
+  }
 }

.stylelintrc.json

@@ -0,0 +1,12 @@
+{
+    "extends": ["stylelint-config-standard"],
+    "rules": {
+        "selector-class-pattern": [
+            "^[a-z]([-]?[a-z0-9]+)*(__[a-z0-9]([-]?[a-z0-9]+)*)?(--[a-z0-9]([-]?[a-z0-9]+)*)?$",
+            {
+                "resolveNestedSelectors": true,
+                "message": "Expected class selector \"%s\" to match BEM CSS pattern https://en.bem.info/methodology/css. Selector validation tool: https://regexr.com/3apms"
+            }
+        ]
+    }
+}

package.json

@@ -122,6 +122,7 @@
 		"@typescript-eslint/parser": "7.4",
 		"axios": "^1.6.2",
 		"chalk": "^5.3.0",
+		"create-stylelint": "^0.5.0",
 		"eslint": "8.57",
 		"eslint-config-prettier": "^7.2.0",
 		"eslint-plugin-prettier": "^3.3.1",
@@ -130,6 +131,8 @@
 		"mri": "^1.2.0",
 		"nyc": "^15.1.0",
 		"prettier": "^2.2.1",
+		"stylelint": "^16.10.0",
+		"stylelint-config-standard": "^36.0.1",
 		"ts-loader": "^8.0.14",
 		"ts-node": "^10.9.2",
 		"typescript": "^5.6"