consolidate Service interface and implementation classes

Oqtane.Client/Services/SearchResultsService.cs

@@ -1,4 +1,3 @@
-using System.Collections.Generic;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Oqtane.Documentation;
@@ -8,6 +7,12 @@ using Oqtane.Shared;
 
 namespace Oqtane.Services
 {
+    [PrivateApi("Mark SearchResults classes as private, since it's not very useful in the public docs")]
+    public interface ISearchResultsService
+    {
+        Task<SearchResults> GetSearchResultsAsync(SearchQuery searchQuery);
+    }
+
     [PrivateApi("Don't show in the documentation, as everything should use the Interface")]
     public class SearchResultsService : ServiceBase, ISearchResultsService, IClientService
     {