chore: separated System.Windows.Interactivity code

src/Shared/System.Windows.Interactivity/TriggerAction`1.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Windows;
+
+namespace HandyControl.Interactivity;
+
+public abstract class TriggerAction<T> : TriggerAction where T : DependencyObject
+{
+    protected TriggerAction() : base(typeof(T))
+    {
+    }
+
+#pragma warning disable 108,114
+    protected T AssociatedObject => (T) base.AssociatedObject;
+#pragma warning restore 108,114
+
+    protected sealed override Type AssociatedObjectTypeConstraint =>
+        base.AssociatedObjectTypeConstraint;
+}