Auto merge of #105160 - nnethercote:rm-Lit-token_lit, r=petrochenkov

Remove `token::Lit` from `ast::MetaItemLit`.

Currently `ast::MetaItemLit` represents the literal kind twice. This PR removes that redundancy. Best reviewed one commit at a time.

r? `@petrochenkov`

compiler/rustc_ast_lowering/src/lib.rs

@@ -958,7 +958,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     lit
                 } else {
                     MetaItemLit {
-                        token_lit: token::Lit::new(token::LitKind::Err, kw::Empty, None),
+                        symbol: kw::Empty,
+                        suffix: None,
                         kind: LitKind::Err,
                         span: DUMMY_SP,
                     }