Implementing support for HIDL native handles in Java

This change implements the equivalent of the C++ native_handle_t type in
Java. Similar to the C++ type, the NativeHandle class wraps an arraylist
of FileDescriptor objects, along with a raw data stream (integer array).

Bug: 35098567
Test: Ran m, hidl_test (C++ and Java). Functionality tests are included
in a separate CL.

Change-Id: Ic53f9a49ae17ce5708577a586230126ab0e222c7
diff --git a/Android.bp b/Android.bp
index 8ac027f..ae0acad 100644
--- a/Android.bp
+++ b/Android.bp
@@ -898,6 +898,7 @@
         "core/java/android/os/IHwInterface.java",
         "core/java/android/os/DeadObjectException.java",
         "core/java/android/os/DeadSystemException.java",
+        "core/java/android/os/NativeHandle.java",
         "core/java/android/os/RemoteException.java",
         "core/java/android/util/AndroidException.java",
     ],
@@ -1444,6 +1445,7 @@
         "core/java/android/os/IHwInterface.java",
         "core/java/android/os/DeadObjectException.java",
         "core/java/android/os/DeadSystemException.java",
+        "core/java/android/os/NativeHandle.java",
         "core/java/android/os/RemoteException.java",
         "core/java/android/util/AndroidException.java",
     ],