Add arrow-body-style ESLint rule

Author: ehmicky

.eslintrc.js

@@ -27,6 +27,7 @@ module.exports = {
     // Those ESLint rules are not enabled by Prettier, ESLint recommended rules
     // nor standard JavaScript. However, they are still useful
     'array-callback-return': [2, { allowImplicit: true, checkForEach: true }],
+    'arrow-body-style': 2,
     'block-scoped-var': 2,
     'class-methods-use-this': 2,
     complexity: [2, 5],