[#24] Client: Implement pool part1

first iteration - base classes and methods

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

src/FrostFS.SDK.ClientV2/Models/Session/FrostFsSessionToken.cs

@@ -1,6 +1,9 @@
+using System;
+
 namespace FrostFS.SDK;
 
-public class FrostFsSessionToken(byte[] token)
+public class FrostFsSessionToken(byte[] token, Guid id)
 {
+    public Guid Id { get; private set; } = id;
     public byte[] Token { get; private set; } = token;
 }