Remove extern crate rustc_macros from numerous crates.

compiler/rustc_session/src/utils.rs

@@ -1,6 +1,7 @@
 use crate::session::Session;
 use rustc_data_structures::profiling::VerboseTimingGuard;
 use rustc_fs_util::try_canonicalize;
+use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use std::{
     path::{Path, PathBuf},
     sync::OnceLock,