Style: Improve code style based on official HA frontend repository

Author: danimart1991

.eslintrc

@@ -1,17 +1,130 @@
 {
-    "env": {
-        "browser": true,
-        "es6": true
+    "extends": [
+      "airbnb-base",
+      "airbnb-typescript/base",
+      "plugin:@typescript-eslint/recommended",
+      "plugin:wc/recommended",
+      "plugin:lit/all",
+      "plugin:lit-a11y/recommended",
+      "prettier"
+    ],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+      "ecmaVersion": 2020,
+      "ecmaFeatures": {
+        "modules": true
+      },
+      "sourceType": "module",
+      "project": "./tsconfig.json"
+    },
+    "settings": {
+      "import/resolver": {
+        "webpack": {
+          "config": "./webpack.config.cjs"
+        }
+      }
     },
-    "extends": "eslint:recommended",
     "globals": {
-        "Atomics": "readonly",
-        "SharedArrayBuffer": "readonly"
+      "__DEV__": false,
+      "__DEMO__": false,
+      "__BUILD__": false,
+      "__VERSION__": false,
+      "__STATIC_PATH__": false,
+      "__SUPERVISOR__": false,
+      "Polymer": true
     },
-    "parserOptions": {
-        "ecmaVersion": 2018,
-        "sourceType": "module"
+    "env": {
+      "browser": true,
+      "es6": true
     },
     "rules": {
-    }
-}
+      "class-methods-use-this": "off",
+      "new-cap": "off",
+      "prefer-template": "off",
+      "object-shorthand": "off",
+      "func-names": "off",
+      "no-underscore-dangle": "off",
+      "strict": "off",
+      "no-plusplus": "off",
+      "no-bitwise": "error",
+      "comma-dangle": "off",
+      "vars-on-top": "off",
+      "no-continue": "off",
+      "no-param-reassign": "off",
+      "no-multi-assign": "off",
+      "no-console": "error",
+      "radix": "off",
+      "no-alert": "off",
+      "no-nested-ternary": "off",
+      "prefer-destructuring": "off",
+      "no-restricted-globals": [2, "event"],
+      "prefer-promise-reject-errors": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off",
+      "import/no-unresolved": "off",
+      "import/no-cycle": "off",
+      "import/extensions": [
+        "error",
+        "ignorePackages",
+        {
+          "ts": "never",
+          "js": "never"
+        }
+      ],
+      "no-restricted-syntax": ["error", "LabeledStatement", "WithStatement"],
+      "object-curly-newline": "off",
+      "default-case": "off",
+      "wc/no-self-class": "off",
+      "no-shadow": "off",
+      "@typescript-eslint/camelcase": "off",
+      "@typescript-eslint/ban-ts-comment": "off",
+      "@typescript-eslint/no-use-before-define": "off",
+      "@typescript-eslint/no-non-null-assertion": "off",
+      "@typescript-eslint/no-explicit-any": "off",
+      "@typescript-eslint/explicit-function-return-type": "off",
+      "@typescript-eslint/explicit-module-boundary-types": "off",
+      "@typescript-eslint/no-shadow": ["error"],
+      "@typescript-eslint/naming-convention": [
+        "off",
+        {
+          "selector": "default",
+          "format": ["camelCase", "snake_case"],
+          "leadingUnderscore": "allow",
+          "trailingUnderscore": "allow"
+        },
+        {
+          "selector": ["variable"],
+          "format": ["camelCase", "snake_case", "UPPER_CASE"],
+          "leadingUnderscore": "allow",
+          "trailingUnderscore": "allow"
+        },
+        {
+          "selector": "typeLike",
+          "format": ["PascalCase"]
+        }
+      ],
+      "@typescript-eslint/no-unused-vars": "off",
+      "unused-imports/no-unused-vars": [
+        "error",
+        {
+          "vars": "all",
+          "varsIgnorePattern": "^_",
+          "args": "after-used",
+          "argsIgnorePattern": "^_",
+          "ignoreRestSiblings": true
+        }
+      ],
+      "unused-imports/no-unused-imports": "error",
+      "lit/attribute-value-entities": "off",
+      "lit/no-template-map": "off",
+      "lit/no-native-attributes": "warn",
+      "lit/no-this-assign-in-render": "warn",
+      "lit-a11y/click-events-have-key-events": ["off"],
+      "lit-a11y/no-autofocus": "off",
+      "lit-a11y/alt-text": "warn",
+      "lit-a11y/anchor-is-valid": "warn",
+      "lit-a11y/role-has-required-aria-attrs": "warn"
+    },
+    "plugins": ["disable", "unused-imports"],
+    "processor": "disable/disable"
+  }