Implement `onbeforeunload` to notify user when leaving Directus App with unsaved content.

Summary Assume: Admin have to add "Share" permission on all tables (100500 in total) on 3 environments (dev/acc/prd) Actual: 1. Admin opens DEV env and navigates to the policy. 2. Admin does those 100500x2 clicks (one click on "Share", second click on "All access" 3. Admin clicks on a subtle green "Save" button. 4. Admin opens ACC env 5. 201000 clicks 6. Clicks Save 7. Admin opens PRD env 8. 201000 clicks 9. Forgots to click SAVE! 10. Types in the address bar the Jira URL and updates the related ticket to done. Result: PRD environment that is misconfigured. To be: 9. Forgots to click SAVE! 10. Types in the address bar the Jira URL -> popup window _"You have unsaved data"_ appears. 11. Clicks "Save" 12. Types in Jira URL and updates the ticket. Result: All envs are configured properly. Basic Example _No response_ Motivation I hate losing results of my work for a simple mistake. …