Show branch info in DAST profiles library

What does this MR do?

With these changes, the branch associated with DAST scans is displayed in the DAST profiles library. When branch does not exist, a warning is displayed along with a link to edit the scan.

How to test this?

1. Enable the dast_branch_selection feature flag.

echo "Feature.enable(:dast_branch_selection)" | rails c

2. Navigate to a project's DAST profiles library at /:namespace/:project/-/security/configuration/dast_profiles.

Screenshots (strongly suggested)

Context	Preview
Current (feature flag disabled)
Branch exists
Branch does not exist

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 #323789 (closed)