Refactor token handling, support server-initiated pairing

BTCPayServer/Data/PairingCodeData.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace BTCPayServer.Data
+{
+    public class PairingCodeData
+    {
+		public string Id
+		{
+			get; set;
+		}
+		
+		public string Facade
+		{
+			get; set;
+		}
+		public string StoreDataId
+		{
+			get; set;
+		}
+		public DateTimeOffset Expiration
+		{
+			get;
+			set;
+		}
+
+		public string Label
+		{
+			get;
+			set;
+		}
+		public string SIN
+		{
+			get;
+			set;
+		}
+		public DateTime DateCreated
+		{
+			get;
+			set;
+		}
+		public string TokenValue
+		{
+			get;
+			set;
+		}
+	}
+}