Add ManagedObjectReferenceManager for CoreCLR

Add a new ManagedObjectReferenceManager that maintains GREF and WREF
counters entirely in managed code using Interlocked operations, with
zero P/Invoke overhead. Logging is disabled (LogGlobalReferenceMessages
and LogLocalReferenceMessages return false). The gref_gc_threshold
check for triggering full GC is preserved.

AndroidObjectReferenceManager is kept unchanged for Mono.
CoreCLR uses ManagedObjectReferenceManager, selected at runtime in
AndroidRuntimeOptions. NativeAOT uses the existing
Java.Interop.ManagedObjectReferenceManager with null log writers.

Author: simonrozsival

src/Microsoft.Android.Runtime.NativeAOT/Java.Interop/JreRuntime.cs

@@ -62,7 +62,7 @@ static NativeAotRuntimeOptions CreateJreVM (NativeAotRuntimeOptions builder)
 #endif  // NET
 
 			builder.ValueManager            ??= ManagedValueManager.GetOrCreateInstance();
-			builder.ObjectReferenceManager  ??= new Android.Runtime.AndroidObjectReferenceManager ();
+			builder.ObjectReferenceManager  ??= new ManagedObjectReferenceManager (null, null);
 
 			if (builder.InvocationPointer != IntPtr.Zero || builder.EnvironmentPointer != IntPtr.Zero)
 				return builder;

src/Mono.Android/Android.Runtime/AndroidRuntime.cs

@@ -13,6 +13,8 @@
 using Java.Interop.Tools.TypeNameMappings;
 using System.Diagnostics.CodeAnalysis;
 
+using RuntimeFeature = Microsoft.Android.Runtime.RuntimeFeature;
+
 #if JAVA_INTEROP
 namespace Android.Runtime {
 
@@ -94,7 +96,9 @@ public AndroidRuntimeOptions (IntPtr jnienv,
 			EnvironmentPointer      = jnienv;
 			ClassLoader             = new JniObjectReference (classLoader, JniObjectReferenceType.Global);
 			InvocationPointer       = vm;
-			ObjectReferenceManager  = new AndroidObjectReferenceManager ();
+			ObjectReferenceManager  = RuntimeFeature.IsCoreClrRuntime
+				? new Java.Interop.ManagedObjectReferenceManager (null, null)
+				: new AndroidObjectReferenceManager ();
 			TypeManager             = typeManager;
 			ValueManager            = valueManager;
 			UseMarshalMemberBuilder = false;

src/Mono.Android/Mono.Android.csproj

@@ -70,6 +70,9 @@
   </ItemGroup>
 
   <ItemGroup>
+    <Compile Include="..\Microsoft.Android.Runtime.NativeAOT\Java.Interop\ManagedObjectReferenceManager.cs">
+      <Link>Java.Interop\ManagedObjectReferenceManager.cs</Link>
+    </Compile>
     <Compile Include="..\..\external\Java.Interop\src\Java.Interop.Tools.TypeNameMappings\Java.Interop.Tools.TypeNameMappings\JavaNativeTypeManager.cs">
       <Link>JavaNativeTypeManager.cs</Link>
     </Compile>