Include the ModuleBuilder in OnModuleBuilding

This allows modules hooking into OnModuleBuilding method to mutate
theirselves at runtime.

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

@@ -126,7 +126,7 @@ namespace Discord.Commands.Builders
                 try
                 {
                     var moduleInstance = ReflectionUtils.CreateObject<IModuleBase>(TypeInfo, service, services);
-                    moduleInstance.OnModuleBuilding(service);
+                    moduleInstance.OnModuleBuilding(service, this);
                 }
                 catch (Exception)
                 {

src/Discord.Net.Commands/IModuleBase.cs

@@ -1,3 +1,5 @@
+using Discord.Commands.Builders;
+
 namespace Discord.Commands
 {
     internal interface IModuleBase
@@ -8,6 +10,6 @@ namespace Discord.Commands
         
         void AfterExecute(CommandInfo command);
 
-        void OnModuleBuilding(CommandService commandService);
+        void OnModuleBuilding(CommandService commandService, ModuleBuilder builder);
     }
 }

src/Discord.Net.Commands/ModuleBase.cs

@@ -1,3 +1,4 @@
+using Discord.Commands.Builders;
 using System;
 using System.Threading.Tasks;
 
@@ -23,7 +24,7 @@ namespace Discord.Commands
         {
         }
 
-        protected virtual void OnModuleBuilding(CommandService commandService)
+        protected virtual void OnModuleBuilding(CommandService commandService, ModuleBuilder builder)
         {
         }
 
@@ -33,11 +34,8 @@ namespace Discord.Commands
             var newValue = context as T;
             Context = newValue ?? throw new InvalidOperationException($"Invalid context type. Expected {typeof(T).Name}, got {context.GetType().Name}");
         }
-
         void IModuleBase.BeforeExecute(CommandInfo command) => BeforeExecute(command);
-
         void IModuleBase.AfterExecute(CommandInfo command) => AfterExecute(command);
-
-        void IModuleBase.OnModuleBuilding(CommandService commandService) => OnModuleBuilding(commandService);
+        void IModuleBase.OnModuleBuilding(CommandService commandService, ModuleBuilder builder) => OnModuleBuilding(commandService, builder);
     }
 }