Use androidx lib for backpressed callback (#20291)

* use androidx lib for backpressed callback

* Update API suppressions

---------

Co-authored-by: Julien Lebosquain <julien@lebosquain.net>
(cherry picked from commit 1ae9694f78)

api/Avalonia.Android.nupkg.xml

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <!-- https://learn.microsoft.com/en-us/dotnet/fundamentals/package-validation/diagnostic-ids -->
 <Suppressions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <Suppression>
@@ -13,4 +13,4 @@
     <Left>baseline/net8.0-android34.0/Avalonia.Android.dll</Left>
     <Right>target/net8.0-android34.0/Avalonia.Android.dll</Right>
   </Suppression>
-</Suppressions>
+</Suppressions>

src/Android/Avalonia.Android/AvaloniaActivity.cs

@@ -21,13 +21,14 @@ namespace Avalonia.Android;
 /// Common implementation of android activity that is integrated with Avalonia views.
 /// If you need a base class for main activity of Avalonia app, see <see cref="AvaloniaMainActivity"/> or <see cref="AvaloniaMainActivity{TApp}"/>.  
 /// </summary>
-public class AvaloniaActivity : AppCompatActivity, IAvaloniaActivity, IOnBackInvokedCallback
+public class AvaloniaActivity : AppCompatActivity, IAvaloniaActivity
 {
     private EventHandler<ActivatedEventArgs>? _onActivated, _onDeactivated;
     private GlobalLayoutListener? _listener;
     private object? _content;
     private bool _contentViewSet;
     internal AvaloniaView? _view;
+    private BackPressedCallback? _currentBackPressedCallback;
 
     public Action<int, Result, Intent?>? ActivityResult { get; set; }
     public Action<int, string[], Permission[]>? RequestPermissionsResult { get; set; }
@@ -132,7 +133,8 @@ public class AvaloniaActivity : AppCompatActivity, IAvaloniaActivity, IOnBackInv
 
         if (OperatingSystem.IsAndroidVersionAtLeast(33))
         {
-            OnBackInvokedDispatcher.UnregisterOnBackInvokedCallback(this);
+            _currentBackPressedCallback?.Remove();
+            _currentBackPressedCallback = null;
         }
 
         base.OnStop();
@@ -144,7 +146,8 @@ public class AvaloniaActivity : AppCompatActivity, IAvaloniaActivity, IOnBackInv
 
         if (OperatingSystem.IsAndroidVersionAtLeast(33))
         {
-            OnBackInvokedDispatcher.RegisterOnBackInvokedCallback(IOnBackInvokedDispatcher.PriorityDefault, this);
+            _currentBackPressedCallback = new BackPressedCallback(this);
+            OnBackPressedDispatcher.AddCallback(this, _currentBackPressedCallback);
         }
         base.OnStart();
     }

src/Android/Avalonia.Android/BackPressedCallback.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using AndroidX.Activity;
+
+namespace Avalonia.Android
+{
+    internal class BackPressedCallback(AvaloniaActivity activity) : OnBackPressedCallback(true)
+    {
+        public override void HandleOnBackPressed()
+        {
+            activity.OnBackInvoked();
+        }
+    }
+}