Fix #20400, Start-Process with -NoNewWindow returns null ExitCode on Process object with -PassThru

[CodeCyclone]

PR Summary

Fixing issue #20400 along with some duplicates.

This issue was introduced by change #19096.
This change moved from .NET creating process objects to use P/Invoke (Windows APIs). The code would fetch the Process object from .NET but by design it throws an exception silently and ExitCode is null because it didn't handle spawning the process itself.

Calling the Handle property on the fetched Process will resolve ExitCode state because it fetches the underlying SafeHandle used to update the ExitCode property.

PR Context

When you call Start-Process with -NoNewWindow, ExitCode will be null. This breaks a lot of customers of PowerShell both internally and externally.

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[iSazonov]

@CodeCyclone Please add test(s) to avoid regressions.

[SteveL-MSFT]

Please add a test in https://github.com/PowerShell/PowerShell/blob/811efa46df822bf7be6179b6219f9f9d160eb7d5/test/powershell/Modules/Microsoft.PowerShell.Management/Start-Process.Tests.ps1

[CodeCyclone]

Added test, addressed feedback on commenting change. Added more detail and referenced issue.
Screenshot of the test failing without my fix:

[SteveL-MSFT]

LGTM

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This PR has 4 quantified lines of changes. In general, a change size of upto 200 lines is ideal for the best PR experience!

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Label      : Extra Small
Size       : +4 -0
Percentile : 1.6%

Total files changed: 2

Change summary by file extension:
.cs : +1 -0
.ps1 : +3 -0

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📣 Hey @CodeCyclone, how did we do? We would love to hear your feedback with the link below! 🗣️

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[Moazzem-Hossain-pixel]

Thanks a lot