Rollup merge of #143997 - Coder-256:stable-mir-macro-hygiene, r=oli-obk

Use $crate in macros for rustc_public (aka stable_mir)

This makes `#[macro_use] extern crate rustc_public` unnecessary (which brings all of `rustc_public`'s macros into scope for the entire crate); instead, now you can simply use `rustc_public::run!()`.