Resolve "New design for user deletion confirmation in admin area"

What does this MR do?

When deleting a user as admin, we should be using a modal instead of a confirmation dialog.

• Add a Vue component for the modal that supports
• Entering the user's name before doing any action
• Allows admin to delete user or delete user and contributions
• Alternatively allows admin to block user
• On /admin/users/ and /admin/users/:username
• Update text to reflect design
• Show appropriate modal when using dropdown for particular user

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #41301 (closed)