WIP ReviewUnusedParameter: 搜索 through child scope

[Christoph Bergmeister (bergmeister)]

PR Summary

Fixes #1472

This is WIP as at the moment, using a parameter in another function would yield a false negative.
An alternative implementation would be to allow only specific child scopes like e.g. the ones from ForEach-Object/Where-Object. I still have to figure out what would be better/easier

PR Checklist

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• Summarized changes
• Change is not breaking
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