Add UnstructuredParcelable trait and macros.

Bug: 303064346
Test: atest aidl_integration_test
Change-Id: I067e05d5f03b678c963ac159574116ef3e33c9ed
diff --git a/libs/binder/rust/src/lib.rs b/libs/binder/rust/src/lib.rs
index 7f9348d..16049f2 100644
--- a/libs/binder/rust/src/lib.rs
+++ b/libs/binder/rust/src/lib.rs
@@ -136,8 +136,8 @@
     pub use crate::native::Binder;
     pub use crate::parcel::{
         BorrowedParcel, Deserialize, DeserializeArray, DeserializeOption, Parcel,
-        ParcelableMetadata, Serialize, SerializeArray, SerializeOption, NON_NULL_PARCELABLE_FLAG,
-        NULL_PARCELABLE_FLAG,
+        ParcelableMetadata, Serialize, SerializeArray, SerializeOption, UnstructuredParcelable,
+        NON_NULL_PARCELABLE_FLAG, NULL_PARCELABLE_FLAG,
     };
     pub use crate::proxy::{AssociateClass, Proxy};
 }