Adding {read,write}Embedded{From,To} methods for hidl_handle

This change implements helper functions for serializing/deserializing
hidl_handle types to/from parcels, similar to the other HIDL types
(hidl_string, hild_string).

Bug: 35098567
Test: Ran the hidl_test suite
Change-Id: I5f6720c42d69a7f760a91442fbdeec202cb2ffcd
diff --git a/transport/include/hidl/HidlBinderSupport.h b/transport/include/hidl/HidlBinderSupport.h
index 6d45f39..97d185e 100644
--- a/transport/include/hidl/HidlBinderSupport.h
+++ b/transport/include/hidl/HidlBinderSupport.h
@@ -49,6 +49,14 @@
     wp<::android::hidl::base::V1_0::IBase> mBase;
 };
 
+// ---------------------- hidl_handle
+
+status_t readEmbeddedFromParcel(const hidl_handle &handle,
+        const Parcel &parcel, size_t parentHandle, size_t parentOffset);
+
+status_t writeEmbeddedToParcel(const hidl_handle &handle,
+        Parcel *parcel, size_t parentHandle, size_t parentOffset);
+
 // ---------------------- hidl_memory
 
 status_t readEmbeddedFromParcel(const hidl_memory &memory,