Added FTX to console example

Examples/ConsoleClient/Exchanges/IExchange.cs

@@ -13,6 +13,7 @@ namespace ConsoleClient.Exchanges
     {
         Task<decimal> GetPrice(string symbol);
         Task<IEnumerable<OpenOrder>> GetOpenOrders();
+        Task<Dictionary<string, decimal>> GetBalances();
         Task<WebCallResult> CancelOrder(string symbol, string id);
         Task<WebCallResult<string>> PlaceOrder(string symbol, string side, string type, decimal quantity, decimal? price );
         Task<UpdateSubscription> SubscribePrice(string symbol, Action<decimal> handler);