Added plugin events

src/HopFrame.Core/Callbacks/ICallbackEmitter.cs

@@ -0,0 +1,14 @@
+namespace HopFrame.Core.Callbacks;
+
+public interface ICallbackEmitter {
+    
+    Guid RegisterCallbackHandler(string @event, Func<object, IServiceProvider, Task> handler);
+    
+    bool RemoveCallbackHandler(Guid id);
+    
+    Task DispatchCallback(string @event, object argument = null!);
+
+    void RemoveAllCallbackHandlers(string @event);
+    void RemoveAllCallbackHandlers();
+
+}