Poll for the result of operations during MSI installation

[Blue (OneBlue)]

Summary of the Pull Request

This change updates the custom action logic to poll for the completion of appx operations during the MSI installations.

Calling .get() registers a delegate that, due to a cppwinrt lifetime issue, might not get released until wslinstall.dll is unloaded, causing a crash since the release will jump into unloaded code.

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[Copilot]

Pull request overview

Updates MSI custom action logic to poll AppX operations safely, avoiding delegate lifetime issues during DLL unloading.

Changes:

• Adds polling-based operation waiting and cleanup.
• Handles error and canceled states.
• Updates deprovisioning and error paths.

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[Ben Hillis (benhillis)]

This definitely seems like a cpp / winrt bug, hopefully we can get a fix or better guidance from them.