chore: add eslint license header plugin

cherry picking changes as requested for PR 1017

Author: coopernetes

.eslintrc.json

@@ -0,0 +1,59 @@
+{
+  "parser": "@typescript-eslint/parser",
+  "env": {
+    "node": true,
+    "browser": true,
+    "commonjs": true,
+    "es2021": true,
+    "mocha": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:react/recommended",
+    "google",
+    "prettier",
+    "plugin:json/recommended"
+  ],
+  "overrides": [
+    {
+      "files": ["test/**/*.js", "**/*.json"],
+      "parser": "espree",
+      "rules": {
+        "@typescript-eslint/no-unused-expressions": "off"
+      }
+    }
+  ],
+  "parserOptions": {
+    "project": "./tsconfig.json",
+    "requireConfigFile": false,
+    "ecmaVersion": 12,
+    "sourceType": "module",
+    "ecmaFeatures": {
+      "jsx": true,
+      "modules": true
+    },
+    "babelOptions": {
+      "presets": ["@babel/preset-react"]
+    }
+  },
+  "plugins": ["@typescript-eslint", "react", "prettier", "license-header"],
+  "rules": {
+    "react/prop-types": "off",
+    "require-jsdoc": "off",
+    "no-async-promise-executor": "off",
+    "@typescript-eslint/no-explicit-any": "off", // temporary until TS refactor is complete
+    "@typescript-eslint/no-unused-vars": "off", // temporary until TS refactor is complete
+    "@typescript-eslint/no-require-imports": "off", // prevents error on old "require" imports
+    "@typescript-eslint/no-unused-expressions": "off", // prevents error on test "expect" expressions
+    "license-header/header": [
+      "error",
+      "./LICENSE_header.txt"
+    ]
+  },
+  "settings": {
+    "react": {
+      "version": "detect"
+    }
+  }
+}

LICENSE_header.txt

@@ -0,0 +1,19 @@
+/**
+ * @license
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */