Auto merge of #116163 - compiler-errors:lazyness, r=oli-obk

Don't store lazyness in `DefKind::TyAlias`

1. Don't store lazyness of a type alias in its `DefKind`, but instead via a query.
2. This allows us to treat type aliases as lazy if `#[feature(lazy_type_alias)]` *OR* if the alias contains a TAIT, rather than having checks for both in separate parts of the codebase.

r? `@oli-obk` cc `@fmease`

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -439,7 +439,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                 DefKind::Struct
                 | DefKind::Ctor(CtorOf::Struct, ..)
                 | DefKind::Union
-                | DefKind::TyAlias { .. }
+                | DefKind::TyAlias
                 | DefKind::AssocTy,
                 _,
             )