Link to auto-fix MRs in PSD widget

What does this MR do?

Implements #247555 (closed)

This adds a link to open auto-fix merge requests in the pipeline status widget above the Project Security Dashboard.

How to test this?

1. Enable the security_auto_fix feature flag:

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

2. Add the GitLab-auto-fix to at least one MR.

3. Navigate to the project's Security Dashboard.

Screenshots (strongly suggested)

Before	After

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry (behind a feature flag)
• [-] 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

Related to #247555 (closed)