Add custom setter to Group property of ModuleBuilder to automatically invoke AddAliases (#1950)

* fix sharded client current user

* add custom setter to group property of module builder

Author: Cenngo

src/Discord.Net.Commands/Builders/ModuleBuilder.cs

@@ -8,6 +8,7 @@ namespace Discord.Commands.Builders
     public class ModuleBuilder
     {
         #region ModuleBuilder
+        private string _group;
         private readonly List<CommandBuilder> _commands;
         private readonly List<ModuleBuilder> _submodules;
         private readonly List<PreconditionAttribute> _preconditions;
@@ -19,7 +20,14 @@ public class ModuleBuilder
         public string Name { get; set; }
         public string Summary { get; set; }
         public string Remarks { get; set; }
-        public string Group { get; set; }
+        public string Group { get => _group;
+            set
+            {
+                _aliases.Remove(_group);
+                _group = value;
+                AddAliases(value);
+            }
+        }
 
         public IReadOnlyList<CommandBuilder> Commands => _commands;
         public IReadOnlyList<ModuleBuilder> Modules => _submodules;

src/Discord.Net.Commands/Builders/ModuleClassBuilder.cs

@@ -118,7 +118,6 @@ private static void BuildModule(ModuleBuilder builder, TypeInfo typeInfo, Comman
                     case GroupAttribute group:
                         builder.Name ??= group.Prefix;
                         builder.Group = group.Prefix;
-                        builder.AddAliases(group.Prefix);
                         break;
                     case PreconditionAttribute precondition:
                         builder.AddPrecondition(precondition);