Use PowerShell 5 to create vcpkg port overlay

[pl4nty]

📖 Description

PowerShell 7 is installed by tests, so it might not be available during vcpkg build. Alternatively, PowerShell 7 could be added to https://github.com/microsoft/winget-cli/tree/master/.config?

🔗 References

Introduced in #6243, found while debugging #6261

🔍 Validation

Reran without PowerShell 7 installed

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated Release Notes (if applicable)
• Updated documentation (if applicable)
• Updated Copilot instructions (if build, architecture, or conventions changed)

📋 Issue Type

• Bug fix
• Feature
• Task

Microsoft Reviewers: Open in CodeFlow

[florelis]

I don't think the script currently works with powershell.exe. We'd have to either update the script to work with both, or add pwsh.exe to the list of build requirements.

[pl4nty]

I've only tested powershell.exe -ExecutionPolicy Bypass -File "$(MSBuildThisFileDirectory)VcpkgPortOverlay\CreatePortOverlay.ps1" -StampFile "$(MSBuildThisFileDirectory)VcpkgPortOverlay\.created" on an existing VM; I'll build a new one to see if the script works