feat(Android): Address rule CA1822

src/Android/Avalonia.Android/Platform/Specific/Helpers/AndroidKeyboardEventsHelper.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Android.Platform.Specific.Helpers
             return DispatchKeyEventInternal(e, out callBase);
         }
 
-        string UnicodeTextInput(KeyEvent keyEvent)
+        static string UnicodeTextInput(KeyEvent keyEvent)
         {
             return keyEvent.Action == KeyEventActions.Multiple
                 && keyEvent.RepeatCount == 0

src/Android/Avalonia.Android/Platform/Storage/AndroidStorageItem.cs

@@ -178,7 +178,7 @@ internal sealed class AndroidStorageFile : AndroidStorageItem, IStorageBookmarkF
         return false;
     }
 
-    private Stream? GetVirtualFileStream(Context context, AndroidUri uri, bool isOutput)
+    private static Stream? GetVirtualFileStream(Context context, AndroidUri uri, bool isOutput)
     {
         var mimeTypes = context.ContentResolver?.GetStreamTypes(uri, FilePickerFileTypes.All.MimeTypes![0]);
         if (mimeTypes?.Length >= 1)