chore: added more core configuration files

.editorconfig

@@ -0,0 +1,12 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = false
+insert_final_newline = false

.eslintignore

@@ -0,0 +1,7 @@
+**/*.d.ts
+**/*.map
+dist
+node_modules
+**/*.json
+/common/**/*
+.yarn

.eslintrc.js

@@ -0,0 +1,129 @@
+require("@rushstack/eslint-patch/modern-module-resolution");
+module.exports = {
+  env: {
+    browser: true,
+    es6: true,
+    jest: true,
+    serviceworker: true
+  },
+  extends: [
+    "airbnb-typescript/base",
+    "plugin:@typescript-eslint/recommended",
+//    "plugin:@typescript-eslint/recommended-requiring-type-checking",
+    "plugin:eslint-comments/recommended",
+    "plugin:promise/recommended",
+    "plugin:wc/recommended",
+    "plugin:lit/recommended",
+    "plugin:unicorn/recommended",
+    "prettier",
+    "prettier/@typescript-eslint"
+  ],
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaFeatures: {
+      jsx: true,
+      modules: true
+    },
+    ecmaVersion: 2020,
+    project: [
+      "./tsconfig.eslint.json"
+    ],
+    sourceType: "module"
+  },
+  plugins: [
+    "@typescript-eslint",
+    "eslint-comments",
+    "import",
+    "lit",
+    "prettier",
+    "promise",
+    "unicorn"
+  ],
+  root: true,
+  rules: {
+    "@typescript-eslint/naming-convention": [
+      "warn",
+      {
+        "format": [
+          "camelCase",
+          "PascalCase",
+          "UPPER_CASE"
+        ],
+        "leadingUnderscore": "allow",
+        "selector": "variable"
+      },
+      {
+        "format": [
+          "camelCase",
+          "PascalCase"
+        ],
+        "leadingUnderscore": "allow",
+        "selector": "function"
+      },
+      {
+        "format": [
+          "PascalCase"
+        ],
+        "selector": "typeLike"
+      }
+    ],
+    "@typescript-eslint/no-non-null-assertion": "off",
+    "@typescript-eslint/no-unused-vars": "warn",
+    "@typescript-eslint/restrict-template-expressions": "off",
+    "import/extensions": [
+      "error",
+      "ignorePackages",
+      {
+        "js": "never",
+        "ts": "never",
+        "jsx": "never",
+        "tsx": "never"
+      }
+    ],
+    "import/prefer-default-export": "off",
+    "no-param-reassign": "off",
+    "no-plusplus": "off",
+    "no-restricted-syntax": [
+      "error",
+      "LabeledStatement",
+      "WithStatement"
+    ],
+    "no-return-assign": [
+      "error",
+      "except-parens"
+    ],
+    "no-underscore-dangle": "off",
+    "prettier/prettier": "error",
+    "quotes": [
+      "warn",
+      "backtick"
+    ],
+    "unicorn/no-nested-ternary": "off",
+    "unicorn/no-useless-undefined": "off",
+    "unicorn/number-literal-case": "off"
+  },
+  "settings": {
+    "import/extensions": [
+      ".js",
+      ".jsx",
+      ".ts",
+      ".tsx"
+    ],
+    "import/parsers": {
+      "@typescript-eslint/parser": [
+        ".ts",
+        ".tsx"
+      ]
+    },
+    "import/resolver": {
+      "node": {
+        "extensions": [
+          ".js",
+          ".jsx",
+          ".ts",
+          ".tsx"
+        ]
+      }
+    }
+  }
+};