Add branch rule component

What does this MR do and why?

Adds a branch rule component in preparation for listing branch rules.

(no changelog added as this feature is behind a feature flag)

Implementation plan

issue	note
Add branch rules GraphQL query (frontend)	:!96754 (merged)
Add branch rule component	👈 this issue
List branch rules	follow-up (pending update to GraphQL endpoint on the backend)

Screenshots or screen recordings

N/A

How to set up and validate locally

No visual changes are expected.

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 #362217 (closed)