[#11] Add Network Snapshot

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

src/FrostFS.SDK.ClientV2/Mappers/Session/Session.cs

@@ -0,0 +1,25 @@
+ 
+using System;
+using Google.Protobuf;
+
+namespace FrostFS.SDK.ClientV2.Mappers.GRPC;
+
+public static class SessionMapper
+{
+    internal static string SerializeSessionToken(this Session.SessionToken token)
+    {
+        byte[] bytes = new byte[token.CalculateSize()];
+        CodedOutputStream stream = new(bytes);
+        token.WriteTo(stream);
+
+        return Convert.ToBase64String(bytes);
+    }
+
+    internal static Session.SessionToken DeserializeSessionToken(this byte[] bytes)
+    {
+        Session.SessionToken token = new();
+        token.MergeFrom(bytes);
+
+        return token;
+    }
+}