feat: add break-on-detections input for build failure on vulnerabilities

[DimaBir]

Summary

• Adds break-on-detections input (default: false) to action.yml
• When enabled, sets MSDO_BREAK=true env var before calling toolkit's client.run()
• Closes Impossible to break the build - not-break-on-detections flag is forcebly added on scan run #156

Dependency

Requires toolkit PR: microsoft/security-devops-actions-toolkit#23
(The toolkit must respect MSDO_BREAK to skip --not-break-on-detections)

Usage

- uses: microsoft/security-devops-action@main
  with:
    break-on-detections: true

Backward compatible

Default is false — no behavior change unless user explicitly opts in.

Test plan

• Default (false): no change in behavior
• Enabled (true): MSDO_BREAK=true set, toolkit skips --not-break-on-detections
• Works with existing inputs (tools, categories, etc.)

ADO: AB#36807380