Use reCaptcha when an issue identified as spam

What does this MR do?

When an issue is identified as a spam it displays a verification page where a user can confirm he/she is a person. If he/she does so the issue is submitted.

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

The complete process of creating an issue (which is identified as a spam) and solving Captcha including the cases when Captcha is not solved / enabled or a case when a new issue closes a discussion on an MR

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

fixes #21518 (closed)