Fix issues with #984, remove extraneous whitespace (#1051)

- Removed unnecessary parameter in SocketVoiceServer

- Moved SocketVoiceServer into Entities/Voice

- Fixed a bug where trying to download the cached guild would throw

- Fixed a potential bug where Discord might not give us a port when
  connecting to voice

src/Discord.Net.WebSocket/Entities/Voice/SocketVoiceServer.cs

@@ -0,0 +1,21 @@
+using System.Diagnostics;
+
+namespace Discord.WebSocket
+{
+    [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
+    public class SocketVoiceServer
+    {
+        public Cacheable<IGuild, ulong> Guild { get; private set; }
+        public string Endpoint { get; private set; }
+        public string Token { get; private set; }
+
+        internal SocketVoiceServer(Cacheable<IGuild, ulong> guild, string endpoint, string token)
+        {
+            Guild = guild;
+            Endpoint = endpoint;
+            Token = token;
+        }
+
+        private string DebuggerDisplay => $"SocketVoiceServer ({Guild.Id})";
+    }
+}