user import improvements

Oqtane.Server/Managers/Interfaces/IUserManager.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Oqtane.Models;
 
@@ -18,6 +19,6 @@ namespace Oqtane.Managers
         User VerifyTwoFactor(User user, string token);
         Task<User> LinkExternalAccount(User user, string token, string type, string key, string name);
         Task<bool> ValidatePassword(string password);
-        Task<bool> ImportUsers(int siteId, int fileId);
+        Task<Dictionary<string, string>> ImportUsers(int siteId, int fileId);
     }
 }