Reassess usages of Path.GetInvalidFileNameChars() and Path.GetInvalidPathChars()

[jozkee]

We should re-evaluate usages of Path.GetInvalidFileNameChars() and Path.GetInvalidPathChars() in dotnet/runtime and get rid of them if we believe there's absolutely no value in having them. They could still be kept for compatibility i.e. to avoid changing the exception type thrown.

Originally posted by @jozkee in #110301

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[jeffhandley]

The next step on this would be to search across the dotnet/runtime other dotnet repos to see if there's any usage of these APIs. If so, we should determine if those use cases are meaningful. If we can't find any meaningful use cases, and potentially update call sites per the findings. See the additional discussion that occurred on #110301 as well.

Putting this in the 10.0.0 milestone since this came up during the course of other discussions, but I'm also marking as help wanted [up-for-grabs] Good issue for external contributors in case a community member is interested in helping with the research.