Check results dtype in index_out (#108167)
This logic exists for index_put and index_add, but for some reason not for `index.out`
Skip testing, as this function is not technically exposed on the Python level.
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### <samp>🤖 Generated by Copilot at c688cfd</samp>
> _`index_out` checks types_
> _avoiding errors in autumn_
> _complex tensors work_
Fixes https://github.com/pytorch/pytorch/issues/107698
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108167
Approved by: https://github.com/albanD
