feat: add outgoing messages to client

Client/Application/Commands/RelayCommand.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
+
+namespace Client.Application.Commands
+{
+    public class RelayCommand : ICommand
+    {
+        private Action<object?> execute;
+        private Func<object?, bool>? canExecute;
+
+        public event EventHandler? CanExecuteChanged
+        {
+            add { CommandManager.RequerySuggested += value; }
+            remove { CommandManager.RequerySuggested -= value; }
+        }
+
+        public RelayCommand(Action<object?> execute, Func<object?, bool>? canExecute = null)
+        {
+            this.execute = execute;
+            this.canExecute = canExecute;
+        }
+
+        public bool CanExecute(object? parameter)
+        {
+            return canExecute == null || canExecute(parameter);
+        }
+
+        public void Execute(object? parameter)
+        {
+            execute(parameter);
+        }
+    }
+}