🧹 Make usage of Microsoft.Management.Infrastructure consistent and reference it only once in CrossCompatibility project

[bergmeister]

PR Summary

This is to have consistency with what we actually already do in the Rules project and its configuration currently applies as it is the 'root' project: https://github.com/PowerShell/PSScriptAnalyzer/blob/master/Rules/Rules.csproj#L18-L2
Since the project depends on CrossCompatibility, we can reference the Microsoft.Management.Infrastructure only once in there to avoid duplication and consistencies that we currently have.

PR Checklist

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• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
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