C#: Add DynamicGodotObject class

Expands to Object.call, Object.set and Object.get for accessing members. This means it can also access members from scripts written in other languages, like GDScript.

(cherry picked from commit bb6814aef0)

modules/mono/glue/Managed/Files/Object.base.cs

@@ -73,11 +73,39 @@ namespace Godot
             disposed = true;
         }
 
+        /// <summary>
+        /// Returns a new <see cref="Godot.SignalAwaiter"/> awaiter configured to complete when the instance
+        /// <paramref name="source"/> emits the signal specified by the <paramref name="signal"/> parameter.
+        /// </summary>
+        /// <param name="source">
+        /// The instance the awaiter will be listening to.
+        /// </param>
+        /// <param name="signal">
+        /// The signal the awaiter will be waiting for.
+        /// </param>
+        /// <example>
+        /// This sample prints a message once every frame up to 100 times.
+        /// <code>
+        /// public override void _Ready()
+        /// {
+        ///     for (int i = 0; i < 100; i++)
+        ///     {
+        ///         await ToSignal(GetTree(), "idle_frame");
+        ///         GD.Print($"Frame {i}");
+        ///     }
+        /// }
+        /// </code>
+        /// </example>
         public SignalAwaiter ToSignal(Object source, string signal)
         {
             return new SignalAwaiter(source, signal, this);
         }
 
+        /// <summary>
+        /// Gets a new <see cref="Godot.DynamicGodotObject"/> associated with this instance.
+        /// </summary>
+        public dynamic DynamicObject => new DynamicGodotObject(this);
+
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal extern static IntPtr godot_icall_Object_Ctor(Object obj);