fix: resolve mutex race conditions and background job issues

[vaind]

Summary

This PR fixes two critical issues affecting CI reliability and device provider functionality:

1. Mutex Race Condition Fix

Resolves intermittent "Access denied" errors when multiple CI jobs simultaneously attempt to create the same Global mutex.

Root Cause: When multiple processes race to create a mutex, one succeeds while others get UnauthorizedAccessException. The previous fix in PR #15 attempted to handle this with OpenExisting() first, but a narrow race window remained:

1. Process A: OpenExisting() → fails (doesn't exist)
2. Process B: OpenExisting() → fails (doesn't exist)
3. Process A: Creates mutex → succeeds
4. Process B: Tries to create mutex → UnauthorizedAccessException

Solution:

• Added retry loop (max 3 attempts with 50ms delay) for mutex creation
• On UnauthorizedAccessException, retry instead of failing
• Process B will successfully open the mutex that Process A created on retry

Testing:

• ✅ All 33 DeviceLock tests pass
• ✅ Includes test with 5 concurrent processes racing to create same mutex
• ✅ Multiple stress test runs - all passed

2. DebugOutputForwarder Background Job Fix

Resolves "An empty pipe element is not allowed" error when commands run with timeout in background jobs.

Root Cause: $this.DebugOutputForwarder was used inside scriptblocks executed via Start-Job, where $this context is lost, resulting in an empty pipe element.

Solution:

• Pass DebugOutputForwarder as parameter to scriptblocks
• Works correctly in both timeout (background job) and non-timeout (direct execution) scenarios

Testing:

• ✅ All 50 Device tests pass (13 skipped due to missing test fixtures)

Changes

• DeviceLockManager.ps1: Added retry mechanism for mutex creation
• DeviceProvider.ps1: Pass DebugOutputForwarder as scriptblock parameter

Related Issues

Fixes intermittent CI failures in sentry-xbox PR #76