Add button to regenerate 2FA codes.

What does this MR do?

Adds a button to the manage 2FA page that lets you generate a new set of codes.

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

I have an inline style style: 'display: inline-block' in the page, not sure if this is acceptable but I can find or create a css class to replace it if needed.

Why was this MR needed?

Partially fixes #48408 (closed). The rest of this issue can't be solved without requiring everyone to reset their 2FA auth codes because they are stored hashed in the db and cannot be shown again after generation.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated#48408 (closed)
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

#48408 (closed)