Add `clippy::result_as_ref_deref` lint

[aleksanderkrauze]

changelog: added new lint result_as_ref_deref

closes #13342

I've added new lint result_as_ref_deref, which mirrors already existing lint option_as_ref_deref and reused its existing check function.

Open question is should this be another lint, or should two of them be merged together? I've asked about it in the original issue (proposing manual_as_ref_deref name), and @Jarcho suggested the same thing (and proposed manual_fallible_as_deref name).

I'm not sure what is clippy's policy regarding renaming lint names, so I opted into just adding new lint and waiting for the review.