Automated tests for listing failed messages

[afprtclr]

Tests for listing failed messages.
Implementation for https://github.com/Particular/PlatformInternals/issues/779

Reviewer Checklist

• Components are broken down into sensible and maintainable sub-components.
• Styles are scoped to the component using it. If multiple components need to share CSS, then a .css file is created containing the shared CSS and imported into component scoped style sections.
• Naming is consistent with existing code, and adequately describes the component or function being introduced
• Only functions utilizing Vue state or lifecycle hooks are named as composables (i.e. starting with 'use');
• No module-level state is being introduced. If so, request the PR author to move the state to the corresponding Pinia store.

[Copilot]

Copilot review overview

🟢 Approval recommended

The added test infrastructure and scenarios consistently exercise the intended failed-message behavior without identified blocking issues.

Review effort: Balanced
Findings: None