The patch adds tests for D216762 and D216762. Tests verify the following: - Events dispatched by the password-validation-inputs component - Password validation - turn-on-scheduled-backups and enable-backup-encryption interactivity modified inputs Additional changes: - adding a head.js file for chrome tests - moving some helper functions used by browser and chrome tests to their respective head.js files Differential Revision: https://phabricator.services.mozilla.com/D216892