Expose binding plugins in a different API.

src/Avalonia.Base/Data/Core/Plugins/BindingPlugins.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+
+namespace Avalonia.Data.Core.Plugins
+{
+    /// <summary>
+    /// Holds a registry of plugins used for bindings.
+    /// </summary>
+    public static class BindingPlugins
+    {
+        /// <summary>
+        /// An ordered collection of property accessor plugins that can be used to customize
+        /// the reading and subscription of property values on a type.
+        /// </summary>
+        public static IList<IPropertyAccessorPlugin> PropertyAccessors => ExpressionObserver.PropertyAccessors;
+
+        /// <summary>
+        /// An ordered collection of validation checker plugins that can be used to customize
+        /// the validation of view model and model data.
+        /// </summary>
+        public static IList<IDataValidationPlugin> DataValidators => ExpressionObserver.DataValidators;
+
+        /// <summary>
+        /// An ordered collection of stream plugins that can be used to customize the behavior
+        /// of the '^' stream binding operator.
+        /// </summary>
+        public static IList<IStreamPlugin> StreamHandlers => ExpressionObserver.StreamHandlers;
+    }
+}