feat(ast): generate node ID setters for enums (#27500)

Generate `set_node_id` alongside `node_id` for AST enums whose variants expose node IDs. This lets transformations restore the original comment owner on rebuilt nodes through the enum API, using the same inline dispatch as the getter.

tasks/ast_tools/src/generators/get_id.rs

@@ -193,6 +193,11 @@ fn generate_for_enum(enum_def: &EnumDef, schema: &Schema) -> Option<TokenStream>
 
     let enum_ty = enum_def.ty_anon(schema);
     let get_doc = format!(" Get [`NodeId`] of [`{}`].", enum_def.name());
+    let set_doc = format!(" Set [`NodeId`] of [`{}`].", enum_def.name());
+    let setters = enum_def.all_variants(schema).map(|variant| {
+        let variant_ident = variant.ident();
+        quote!( Self::#variant_ident(it) => it.set_node_id(node_id) )
+    });
 
     Some(quote! {
         ///@@line_break
@@ -204,6 +209,14 @@ fn generate_for_enum(enum_def: &EnumDef, schema: &Schema) -> Option<TokenStream>
                     #(#matches),*
                 }
             }
+
+            #[doc = #set_doc]
+            #maybe_inline
+            pub fn set_node_id(&self, node_id: NodeId) {
+                match self {
+                    #(#setters),*
+                }
+            }
         }
     })
 }