Create Read Update and Delete

[brytebee]

I implemented the CRUD (create, read, update, delete) methods.

In this PR, I

• Removed all hardcoded items from the tasks array.
• Implemented a function for adding a new task (add a new element to the array).
• Implemented a function for editing task descriptions.
• Implemented a function for deleting a task (remove an element from the array).
• Implemented a function for the "Clear all completed" button (use filter() method).
• Deleting a task should updates all remaining items' indexes, so they represent the current list order and are unique.
• Persist all changes to the To-Do List in local storage.

[brytebee]

Thanks 🙏

Thanks for the timely code review.