List branch rules under repository settings

What does this MR do and why?

This is the first iteration for listing branch rules under repository settings.

Screenshots or screen recordings

list	empty state

How to set up and validate locally

1. Enable the branch_rules feature flag
2. Configure a protected branch
3. Navigate to Setting > Repository > Branch rules

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.
• UX review

Related to #362217 (closed)