[#24] Client: Implement pool part1

first iteration - base classes and methods

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

src/FrostFS.SDK.ClientV2/Parameters/CallContext.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Security.Cryptography;
+using System.Threading;
+
+using FrostFS.SDK.Cryptography;
+
+using Google.Protobuf;
+
+using Grpc.Core.Interceptors;
+
+namespace FrostFS.SDK.ClientV2;
+
+public class CallContext()
+{
+    private ReadOnlyCollection<Interceptor>? interceptors;
+
+    private ByteString? publicKeyCache;
+
+    public ECDsa? Key { get; set; }
+
+    public FrostFsOwner? OwnerId { get; set; }
+
+    public FrostFsVersion? Version { get; set; }
+
+    public CancellationToken CancellationToken { get; set; }
+
+    public TimeSpan Timeout { get; set; }
+
+    public DateTime? Deadline => Timeout.Ticks > 0 ? DateTime.UtcNow.Add(Timeout) : null;
+
+    public Action<CallStatistics>? Callback { get; set; }
+
+    public ReadOnlyCollection<Interceptor>? Interceptors
+    {
+        get { return this.interceptors; }
+        set { this.interceptors = value; }
+    }
+
+    public ByteString? GetPublicKeyCache()
+    {
+        if (publicKeyCache == null && Key != null)
+        {
+            publicKeyCache = ByteString.CopyFrom(Key.PublicKey());
+        }
+
+        return publicKeyCache;
+    }
+}