Auto merge of #135278 - tgross35:ignore-std-dep-crates, r=SparrowLii

Exclude dependencies of `std` for diagnostics

Currently crates in the sysroot can show up in diagnostic suggestions, such as in rust-lang/rust#135232. To prevent this, duplicate `all_traits` into `visible_traits` which only shows traits in non-private crates.

Setting `#![feature(rustc_private)]` overrides this and makes items in private crates visible as well, since `rustc_private` enables use of `std`'s private dependencies.

This may be reviewed per-commit.

Fixes: rust-lang/rust#135232

Author: bors