Introduced IUnsubscriptionService and replaced the usage in rendering page view model.

Wino.Core.Domain/Interfaces/IUnsubscriptionService.cs

@@ -0,0 +1,15 @@
+using System.Threading.Tasks;
+using Wino.Core.Domain.Models.Reader;
+
+namespace Wino.Core.Domain.Interfaces
+{
+    public interface IUnsubscriptionService
+    {
+        /// <summary>
+        /// Unsubscribes from the subscription using one-click method.
+        /// </summary>
+        /// <param name="info">Unsubscribtion information.</param>
+        /// <returns>Whether the unsubscription is succeeded or not.</returns>
+        Task<bool> OneClickUnsubscribeAsync(UnsubscribeInfo info);
+    }
+}