[HybridWebView] fix trimmer warnings on Android

src/Core/AndroidNative/maui/src/main/java/com/microsoft/maui/HybridJavaScriptInterface.java

@@ -0,0 +1,7 @@
+package com.microsoft.maui;
+
+import androidx.annotation.NonNull;
+
+public interface HybridJavaScriptInterface {
+    void sendMessage(@NonNull String message);
+}

src/Core/src/Handlers/HybridWebView/HybridWebViewHandler.Android.cs

@@ -35,7 +35,7 @@ protected override AWebView CreatePlatformView()
 			return platformView;
 		}
 
-		private sealed class HybridWebViewJavaScriptInterface : Java.Lang.Object
+		private sealed class HybridWebViewJavaScriptInterface : Java.Lang.Object, IHybridJavaScriptInterface
 		{
 			private readonly WeakReference<HybridWebViewHandler> _hybridWebViewHandler;
 
@@ -47,7 +47,6 @@ public HybridWebViewJavaScriptInterface(HybridWebViewHandler hybridWebViewHandle
 			private HybridWebViewHandler? Handler => _hybridWebViewHandler is not null && _hybridWebViewHandler.TryGetTarget(out var h) ? h : null;
 
 			[JavascriptInterface]
-			[Export("sendMessage")]
 			public void SendMessage(string message)
 			{
 				Handler?.VirtualView?.MessageReceived(message);

src/Core/src/Transforms/Metadata.xml

@@ -2,13 +2,15 @@
   <!-- Normalize the namespace for .NET -->
   <attr path="//package[@name='com.microsoft.maui']" name="managedName">Microsoft.Maui</attr>
 
-  <!-- Make all classes internal by default -->
+  <!-- Make all types internal by default -->
   <attr path="//class[@visibility='public']" name="visibility">internal</attr>
-  <!-- Public classes -->
+  <attr path="//interface[@visibility='public']" name="visibility">internal</attr>
+  <!-- Public types -->
   <attr path="//class[@name='PlatformAppCompatTextView']" name="visibility">public</attr>
   <attr path="//class[@name='PlatformContentViewGroup']" name="visibility">public</attr>
   <attr path="//class[@name='PlatformWrapperView']" name="visibility">public</attr>
   <attr path="//class[@name='MauiViewGroup']" name="visibility">public</attr>
+  <attr path="//interface[@name='ImageLoaderCallback']" name="visibility">public</attr>
   <!-- Internal methods & constructors -->
   <attr path="//class[@name='PlatformAppCompatTextView']/method" name="visibility">internal</attr>
   <attr path="//class[@name='PlatformAppCompatTextView']/constructor" name="visibility">internal</attr>