dotnetup: Better error handling for invalid component spec

[dsplaisted]

Once both #53290 and #53163 are merged, we should apply the feedback in this comment:

I think it would be best to do DotnetInstallException with a custom error tag / subtype for this situation, then we can just throw it and we don't need to keep track of whether it is a user error or not in multiple places, nor do we need to return 1 at that point or record the failure.

#53163 I should have fixed the logic which categorizes the nonexception failures, which I've now done here. Probably what this PR will want to use.