Auto merge of #91924 - Aaron1011:serialize-adt-def, r=michaelwoerister

Fully serialize AdtDef

This avoids needing to invoke the `adt_def` query during
the decoding of another query's result.

Split out from https://github.com/rust-lang/rust/pull/91919
See https://github.com/rust-lang/rust/issues/91696#issuecomment-993043710

compiler/rustc_middle/src/ty/mod.rs

@@ -1472,7 +1472,7 @@ pub struct Destructor {
 }
 
 bitflags! {
-    #[derive(HashStable)]
+    #[derive(HashStable, TyEncodable, TyDecodable)]
     pub struct VariantFlags: u32 {
         const NO_VARIANT_FLAGS        = 0;
         /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
@@ -1484,7 +1484,7 @@ bitflags! {
 }
 
 /// Definition of a variant -- a struct's fields or an enum variant.
-#[derive(Debug, HashStable)]
+#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
 pub struct VariantDef {
     /// `DefId` that identifies the variant itself.
     /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
@@ -1586,7 +1586,7 @@ pub enum VariantDiscr {
     Relative(u32),
 }
 
-#[derive(Debug, HashStable)]
+#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
 pub struct FieldDef {
     pub did: DefId,
     #[stable_hasher(project(name))]