Refactor form sections

What does this MR do and why?

This is a simple refactoring which moves the title and description fields into its own section.

Screenshots or screen recordings

No visual changes.

How to set up and validate locally

1. Navigate to /-/security/vulnerabilities/new through the URL (should be a project scope)
2. The page should render the title, description and details section

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 #301003 (closed)