Fix: Don't depend on WebSocket for Interaction service (#2912)

* unfuck interaction service to not depend on WS

* Add XML docs

* fix summary refs

src/Discord.Net.Rest/DiscordRestClient.cs

@@ -15,7 +15,7 @@ namespace Discord.Rest
     /// <summary>
     ///     Provides a client to send REST-based requests to Discord.
     /// </summary>
-    public class DiscordRestClient : BaseDiscordClient, IDiscordClient
+    public class DiscordRestClient : BaseDiscordClient, IDiscordClient, IRestClientProvider
     {
         #region DiscordRestClient
         private RestApplication _applicationInfo;
@@ -399,5 +399,7 @@ namespace Discord.Rest
         async Task<IReadOnlyCollection<IApplicationCommand>> IDiscordClient.BulkOverwriteGlobalApplicationCommand(ApplicationCommandProperties[] properties, RequestOptions options)
             => await BulkOverwriteGlobalCommands(properties, options).ConfigureAwait(false);
         #endregion
+
+        DiscordRestClient IRestClientProvider.RestClient => this;
     }
 }

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

@@ -118,5 +118,9 @@ namespace Discord.Rest
         //IAutocompleteInteraction
         /// <inheritdoc/>
         IAutocompleteInteractionData IAutocompleteInteraction.Data => Data;
+
+        /// <inheritdoc/>
+        Task IAutocompleteInteraction.RespondAsync(IEnumerable<AutocompleteResult> result, RequestOptions options)
+            =>Task.FromResult(Respond(result, options));
     }
 }

src/Discord.Net.Rest/IRestClientProvider.cs

@@ -0,0 +1,14 @@
+using Discord.Rest;
+
+namespace Discord.Rest;
+
+/// <summary>
+///     An interface that represents a client provider for Rest-based clients.
+/// </summary>
+public interface IRestClientProvider
+{
+    /// <summary>
+    ///     Gets the Rest client of this provider.
+    /// </summary>
+    DiscordRestClient RestClient { get; }
+}