add autocomplete respond method to IAutocompleteInteraction

src/Discord.Net.Core/Entities/Interactions/SlashCommands/IAutocompleteInteraction.cs

@@ -1,3 +1,6 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
 namespace Discord
 {
     /// <summary>
@@ -9,5 +12,21 @@ public interface IAutocompleteInteraction : IDiscordInteraction
         ///     Gets the autocomplete data of this interaction.
         /// </summary>
         new IAutocompleteInteractionData Data { get; }
+
+        /// <summary>
+        ///     Responds to this interaction with a set of choices.
+        /// </summary>
+        /// <param name="result">
+        ///     The set of choices for the user to pick from.
+        ///     <remarks>
+        ///         A max of 20 choices are allowed. Passing <see langword="null"/> for this argument will show the executing user that
+        ///         there is no choices for their autocompleted input.
+        ///     </remarks>
+        /// </param>
+        /// <param name="options">The request options for this response.</param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation of responding to this interaction.
+        /// </returns>
+        Task RespondAsync(IEnumerable<AutocompleteResult> result, RequestOptions options = null);
     }
 }

src/Discord.Net.Rest/Entities/Interactions/SlashCommands/RestAutocompleteInteraction.cs

@@ -131,5 +131,9 @@ public override string Respond(string text = null, Embed[] embeds = null, bool i
         //IAutocompleteInteraction
         /// <inheritdoc/>
         IAutocompleteInteractionData IAutocompleteInteraction.Data => Data;
+
+        /// <inheritdoc/>
+        Task IAutocompleteInteraction.RespondAsync(IEnumerable<AutocompleteResult> result, RequestOptions options)
+            => Task.FromResult(Respond(result, options));
     }
 }