PR Summary

Previous code was incorrectly detecting if $PSHOME was in front using .Contains() since a preview would have the path "$PSHOME\preview" in front. Since this affects startup, we don't want to do a bunch of string manipulation with Split() so to cover the most common case we just check if the start of $env:PATH contains $PSHOME with the path separator and if not add to front. Two scenarios that aren't covered:

• If $PSHOME is somewhere else in $env:PATH it will be duplicated. This is unlikely and will just have a small perf impact searching $env:PATH.
• If $env:PATH only contains $PSHOME (without the path separator), then it'll also be duplicated, but this is also unlikely with minor impact.

PR Context

PR Checklist

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• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
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