Check license header using eslint (#2780)

Signed-off-by: Jari Kolehmainen <jari.kolehmainen@gmail.com>

.eslintrc.js

@@ -1,3 +1,24 @@
+/**
+ * Copyright (c) 2021 OpenLens Authors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
 const packageJson = require("./package.json");
 
 module.exports = {
@@ -27,9 +48,11 @@ module.exports = {
         sourceType: "module",
       },
       plugins: [
-        "unused-imports"
+        "header",
+        "unused-imports",
       ],
       rules: {
+        "header/header": [2, "./license-header"],
         "indent": ["error", 2, {
           "SwitchCase": 1,
         }],
@@ -72,6 +95,7 @@ module.exports = {
         "plugin:@typescript-eslint/recommended",
       ],
       plugins: [
+        "header",
         "unused-imports"
       ],
       parserOptions: {
@@ -79,6 +103,7 @@ module.exports = {
         sourceType: "module",
       },
       rules: {
+        "header/header": [2, "./license-header"],
         "no-invalid-this": "off",
         "@typescript-eslint/no-invalid-this": ["error"],
         "@typescript-eslint/explicit-function-return-type": "off",
@@ -127,6 +152,7 @@ module.exports = {
       ],
       parser: "@typescript-eslint/parser",
       plugins: [
+        "header",
         "unused-imports"
       ],
       extends: [
@@ -139,6 +165,7 @@ module.exports = {
         jsx: true,
       },
       rules: {
+        "header/header": [2, "./license-header"],
         "no-invalid-this": "off",
         "@typescript-eslint/no-invalid-this": ["error"],
         "@typescript-eslint/explicit-function-return-type": "off",