Check license header using eslint (#2780)

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

package.json

@@ -315,6 +315,7 @@
     "electron-builder": "^22.10.5",
     "electron-notarize": "^0.3.0",
     "eslint": "^7.7.0",
+    "eslint-plugin-header": "^3.1.1",
     "eslint-plugin-react": "^7.21.5",
     "eslint-plugin-unused-imports": "^1.0.1",
     "file-loader": "^6.0.0",