Draft: PoC: Rearchitect Security Configuration table

What does this MR do?

A proof-of-concept for a (slightly) different architecture of the Security Configuration table, for #322624 (closed).

This MR is formed of three commits, and the messages of those commits tell the story. I recommend reading them, and reviewing this MR commit-by-commit.

In broad strokes, these three commits:

1. Add pinning tests to lock down the complete behaviour of the current implementation
2. Add the new implementation alongside the current one
3. Flip a flag to swap the current implementation for the new, and update the snapshot/pin tests, demonstrating they're functionally the same.

Screenshots (strongly suggested)

n/a

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• 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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #322624 (closed)