Add CQRS Messaging.

PSManagement.SharedKernel/CQRS/Commands/ICommand.cs

+using MediatR;
+
+namespace PSManagement.SharedKernel.CQRS.Command
+{
+    public interface ICommand<out TResponse> : IRequest<TResponse>
+    {
+    }
+}

PSManagement.SharedKernel/CQRS/Commands/ICommandHandler.cs

+using MediatR;
+
+namespace PSManagement.SharedKernel.CQRS.Command
+{
+    public interface ICommandHandler<in TCommand, TResponse> : IRequestHandler<TCommand, TResponse>
+                         where TCommand : ICommand<TResponse>
+    {
+    }
+}

PSManagement.SharedKernel/CQRS/Queries/IQuery.cs

+using MediatR;
+
+namespace PSManagement.SharedKernel.CQRS.Query
+{
+    public interface IQuery<out TResponse> : IRequest<TResponse>
+    {
+    }
+}

PSManagement.SharedKernel/CQRS/Queries/IQueryHandler.cs

+using MediatR;
+
+namespace PSManagement.SharedKernel.CQRS.Query
+{
+    public interface IQueryHandler<in TQuery, TResponse> : IRequestHandler<TQuery, TResponse>
+    where TQuery : IQuery<TResponse>
+    {
+    }
+}