[Java.Interop] CreatePeer() must satisfy targetType

[jonpryor]

Context: dotnet/android#9747
Context: https://discord.com/channels/732297728826277939/732297837953679412/1339638847864176640
Context: https://discord.com/channels/732297728826277939/732297837953679412/1340011105510101063

While trying to get a MAUI sample running atop NativeAOT, we're observing the following crash:

E AndroidRuntime: net.dot.jni.internal.JavaProxyThrowable: System.InvalidCastException: Arg_InvalidCastException
E AndroidRuntime:    at Java.Lang.Object._GetObject[T](IntPtr, JniHandleOwnership) + 0x64
E AndroidRuntime:    at Microsoft.Maui.WindowOverlay.Initialize() + 0x168

Further investigation shows that the crash is from accessing the Activity.WindowManager property:

namespace Android.App;
partial class Activity {
  public virtual unsafe Android.Views.IWindowManager? WindowManager {
    // Metadata.xml XPath method reference: path="/api/package[@name='android.app']/class[@name='Activity']/method[@name='getWindowManager' and count(parameter)=0]"
    [Register ("getWindowManager", "()Landroid/view/WindowManager;", "GetGetWindowManagerHandler")]
    get {
      const string __id = "getWindowManager.()Landroid/view/WindowManager;";
      try {
        var __rm = _members.InstanceMethods.InvokeVirtualObjectMethod (__id, this, null);
        return global::Java.Lang.Object.GetObject<Android.Views.IWindowManager> (__rm.Handle, JniHandleOwnership.TransferLocalRef);
      } finally {
      }
    }
  }
}

Object.GetObject<T>() is now a wrapper around
JniRuntime.JniValueManager.GetPeer(), so the problem, rephrased, is that this:

var peer = JniEnvironment.Runtime.ValueManager.GetPeer (
    ref h,
    JniObjectReferenceOptions.CopyAndDispose,
    targetType:typeof (IWindowManager));

returns a value which does not implement IWindowManager. It was, in fact, returning a Java.Lang.Object instance (!).

The cause of the bug is that JniRuntime.JniValueManager.CreatePeer() was not checking that the Type returned form
Runtime.TypeManager.GetType(JniTypeSignature) was compatible with targetType; instead, it returned the first type in the inheritance chain that had an activation constructor. This was Java.Lang.Object.

Later, when _GetObject<T>() tried to cast the return value of JniRuntime.JniValueManager.GetPeer() to IWindowManager, it failed.

Fix this by updating CreatePeer() to check that the Type from JniRuntime.JniTypeManager.GetType(JniTypeSignature) is assignable to targetType. This ensures that we don't return a Java.Lang.Object instance, allowing the cast to succeed.

Update JniRuntimeJniValueManagerContract to test these new semantics.

[jonpryor]

/azp run

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