Adds a new `security_dashboard_layout` component

What does this MR do?

This Merge Request adds a new <security-dashboard-layout /> component. It doesn't get used anywhere yet, but many MRs make light work.

This component is a simple layout component that should help remove some of the complexity from our current security dashboards. It also helps pave the way for the new first class vulnerabilities.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done