Add event for autocomplete interaction (discord-net#214)

src/Discord.Net.WebSocket/BaseSocketClient.Events.cs

@@ -469,7 +469,7 @@ public event Func<SocketGuildChannel, string, Task> InviteDeleted
 
         #region Interactions
         /// <summary>
-        ///     Fired when an Interaction is created. This event covers all types of interactions including but not limited to: buttons, select menus, slash commands.
+        ///     Fired when an Interaction is created. This event covers all types of interactions including but not limited to: buttons, select menus, slash commands, autocompletes.
         /// </summary>
         /// <remarks>
         ///     <para>
@@ -535,6 +535,15 @@ public event Func<SocketMessageCommand, Task> MessageCommandExecuted
             remove => _messageCommandExecuted.Remove(value);
         }
         internal readonly AsyncEvent<Func<SocketMessageCommand, Task>> _messageCommandExecuted = new AsyncEvent<Func<SocketMessageCommand, Task>>();
+        /// <summary>
+        ///     Fired when an autocomplete is used and its interaction is received.
+        /// </summary>
+        public event Func<SocketAutocompleteInteraction, Task> AutocompleteExecuted
+        {
+            add => _autocompleteExecuted.Add(value);
+            remove => _autocompleteExecuted.Remove(value);
+        }
+        internal readonly AsyncEvent<Func<SocketAutocompleteInteraction, Task>> _autocompleteExecuted = new AsyncEvent<Func<SocketAutocompleteInteraction, Task>>();
 
         /// <summary>
         ///     Fired when a guild application command is created.

src/Discord.Net.WebSocket/DiscordShardedClient.cs

@@ -466,6 +466,7 @@ private void RegisterEvents(DiscordSocketClient client, bool isPrimary)
             client.SlashCommandExecuted += (arg) => _slashCommandExecuted.InvokeAsync(arg);
             client.UserCommandExecuted += (arg) => _userCommandExecuted.InvokeAsync(arg);
             client.MessageCommandExecuted += (arg) => _messageCommandExecuted.InvokeAsync(arg);
+            client.AutocompleteExecuted += (arg) => _autocompleteExecuted.InvokeAsync(arg);
 
             client.ThreadUpdated += (thread1, thread2) => _threadUpdated.InvokeAsync(thread1, thread2);
             client.ThreadCreated += (thread) => _threadCreated.InvokeAsync(thread);

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -2125,6 +2125,9 @@ private async Task ProcessMessageAsync(GatewayOpCode opCode, int? seq, string ty
                                             case SocketMessageCommand messageCommand:
                                                 await TimedInvokeAsync(_messageCommandExecuted, nameof(MessageCommandExecuted), messageCommand).ConfigureAwait(false);
                                                 break;
+                                            case SocketAutocompleteInteraction autocomplete:
+                                                await TimedInvokeAsync(_autocompleteExecuted, nameof(AutocompleteExecuted), autocomplete).ConfigureAwait(false);
+                                                break;
                                         }
                                     }
                                     else