[#14] Add interceptors

Signed-off-by: Pavel Gross <p.gross@yadro.com>

src/FrostFS.SDK.ModelsV2/Context.cs

@@ -1,13 +1,26 @@
 using System;
+using System.Collections.Generic;
 using System.Threading;
+using FrostFS.SDK.ModelsV2;
+using Grpc.Core.Interceptors;
 
 namespace FrostFS.SDK.ClientV2;
 
 public class Context()
 {
+    private List<Interceptor> interceptors;
+
     public CancellationToken CancellationToken { get; set; } = default;
     public TimeSpan Timeout { get; set; } = default;
     public string SessionToken { get; set; } = string.Empty;
 
     public DateTime? Deadline => Timeout.Ticks > 0 ? DateTime.UtcNow.Add(Timeout) : null;
+
+    public Action<CallStatistics> Callback { get; set; }
+
+    public List<Interceptor> Interceptors
+    {
+        get { return interceptors ??= []; }
+        set { interceptors = value; }
+    }  
 }