WebUI: migrate ESLint rules

https://eslint.style/guide/migration

PR #20727.

src/webui/www/.eslintrc.json

@@ -3,13 +3,19 @@
         "browser": true,
         "es2022": true
     },
-    "extends": "eslint:recommended",
+    "extends": [
+        "eslint:recommended",
+        "plugin:@stylistic/disable-legacy"
+    ],
     "plugins": [
-        "html"
+        "html",
+        "@stylistic"
     ],
     "rules": {
         "eqeqeq": "error",
-        "no-mixed-operators": [
+        "no-undef": "off",
+        "no-unused-vars": "off",
+        "@stylistic/no-mixed-operators": [
             "error",
             {
                 "groups": [
@@ -17,9 +23,7 @@
                 ]
             }
         ],
-        "no-undef": "off",
-        "no-unused-vars": "off",
-        "nonblock-statement-body-position": ["error", "below"],
-        "semi": "error"
+        "@stylistic/nonblock-statement-body-position": ["error", "below"],
+        "@stylistic/semi": "error"
     }
 }

src/webui/www/package.json

@@ -11,6 +11,7 @@
     "lint": "eslint private/*.html private/scripts/*.js private/views/*.html public/*.html public/scripts/*.js && stylelint **/*.css && html-validate private public"
   },
   "devDependencies": {
+    "@stylistic/eslint-plugin": "*",
     "eslint": "^8",
     "eslint-plugin-html": "^8",
     "html-validate": "*",