Auto merge of #127543 - carbotaniuman:more_unsafe_attr_verification, r=estebank,traviscross

More unsafe attr verification

This code denies unsafe on attributes such as `#[test]` and `#[ignore]`, while also changing the `MetaItem` parsing so `unsafe` in args like `#[allow(unsafe(dead_code))]` is not accidentally allowed.

Tracking:

- rust-lang/rust#123757

Author: bors