Lint suggestion: warn on use statements already imported via the prelude

[burtonageo]

A large number of traits, types and functions are imported into a rust crate implicitly through the standard prelude. However, when you explicitly bring one of these items in the prelude into scope using the use statement, the rust compiler doesn't warn that the use is unnecessary.

A clippy warning for this could help shave unnecessary lines. This should probably not run on crates with #![no_std]

[yaahc]

This came up in our libs team yesterday when discussing rust-lang/rust#82786. Josh summarized our conclusion but the gist is we want to rely on inherent traits but we expect that inherent traits to accomplish the PR's goal because it won't introduce a ton of new warnings the way the PR's implementation does, but this will have a similar issue to items in the prelude where it's possible to have unused imports that don't produce warnings.

Our suggestion was to add an allow by default lint to warn about these unnecessary imports, and to have it work for both prelude items and inherent traits.