ShowWindow only works on Windows

[sdwheeler]

PR Summary

ShowWindow only works on Windows

• Fixes AB#198683

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[learn-build-service-prod]

Learn Build status updates of commit 4c40f5e:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/7.2/Microsoft.PowerShell.Core/Get-Help.md	✅Succeeded	View (powershell-7.2)
reference/7.3/Microsoft.PowerShell.Core/Get-Help.md	✅Succeeded	View (powershell-7.3)
reference/7.4/Microsoft.PowerShell.Core/Get-Help.md	✅Succeeded	View (powershell-7.4)

For more details, please refer to the build report.

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