Enable lint enforcement on e2e tests and fix the existing errors (#5229)

* Add `e2e` folder to lint scripts

* Fix or add exceptions to all new linting errors

* fix an oopsie 👀

e2e/tests/plugins/ExportAsJSON/exportAsJson.e2e.spec.js

@@ -25,6 +25,8 @@ This test suite is dedicated to tests which verify the basic operations surround
 */
 
 const { test } = require('../../../fixtures.js');
+// FIXME: Remove this eslint exception once tests are implemented
+// eslint-disable-next-line no-unused-vars
 const { expect } = require('@playwright/test');
 
 test.describe('ExportAsJSON', () => {