Refactor command handlers and Startup

src/AppCommon/FileTime.App.Core.Abstraction/Services/ICommandHandler.cs

@@ -0,0 +1,10 @@
+using FileTime.App.Core.Command;
+
+namespace FileTime.App.Core.Services
+{
+    public interface ICommandHandler
+    {
+        bool CanHandleCommand(Commands command);
+        Task HandleCommandAsync(Commands command);
+    }
+}