Remove pretty-printing traits.

`call_with_pp_support_ast` and `call_with_pp_support_hir` how each have
a single call site. This commit inlines and removes them, which also
removes the need for all the supporting traits: `Sess`,
`AstPrinterSupport`, and `HirPrinterSupport`. The `sess` member is also
removed from several structs.

compiler/rustc_driver_impl/src/lib.rs

@@ -12,7 +12,6 @@
 #![feature(lazy_cell)]
 #![feature(let_chains)]
 #![feature(panic_update_hook)]
-#![feature(trait_upcasting)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]
 #![deny(rustc::untranslatable_diagnostic)]