Write-Warning instead of returning artificial DiagnosticRecord when type parsing errors occurs since those DiagnosticRecords cannot be suppressed.

[bergmeister]

PR Summary

Fixes #1041 as per title and enhances message.
I tried looking into being able to support suppressions for a DiagnosticRecord but this did not seem to be possible or very complicated. Since TypeNotFound is not a rule, I think it was confusing anyway to return an object. Consumers like PowerShellEditorServices should check their warning streams to propagate the information to their users. cc @TylerLeonhardt @rjmholt
The failing tests on Ubuntu happen on development as well and seem to be due to an image update (again)

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[JamesWTruher]

I'm pretty sure this isn't the right approach here. We could create different types of diagnostic records, or create some way to suppress these, but these shouldn't be taking these out of the result stream. They're important, and by putting them in the warning stream, they're completely lost.

[bergmeister]

@JamesWTruher I tried looking into a way of suppressing them at first but struggled to do so due to the suppression logic being so complex, maybe you can give it a try please?

[bergmeister]

Will close this in favour of #1130