Add ability to delete a work item note

What does this MR do and why?

This MR implements deleting work item notes.

Screenshots or screen recordings

Deleting a single note in the thread

delete_single_note

Deleting replies to the thread

delete_replies

Error when deleting a note

Known issue: our alert is not sticky so it's not obvious to the user what has happened when note deletion fails

delete_error

How to set up and validate locally

1. Enable the work items MVC feature flag

   Feature.enable(:work_items_mvc)

2. Open any work item
3. Add a few notes
4. On the note, click on three dots on the right top corner and select "Delete comment"

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #389968 (closed)