Added RPC channel and guild entities, Get and Select methods

src/Discord.Net.Rpc/API/Rpc/SelectChannelParams.cs

@@ -0,0 +1,13 @@
+#pragma warning disable CS1591
+using Newtonsoft.Json;
+
+namespace Discord.API.Rpc
+{
+    public class SelectChannelParams
+    {
+        [JsonProperty("channel_id")]
+        public ulong? ChannelId { get; set; }
+        [JsonProperty("force")]
+        public Optional<bool> Force { get; set; }
+    }
+}