Make DI registration public and fix minor essues

Author: A-Programmer

src/KSFramework/KSMessaging/Extensions/RegisterMediatorServices.cs

@@ -78,7 +78,7 @@ public static IServiceCollection AddKSMediator(this IServiceCollection services,
         return services;
     }
 
-    private static void RegisterAllImplementationsOf<TInterface>(this IServiceCollection services,
+    public static IServiceCollection RegisterAllImplementationsOf<TInterface>(this IServiceCollection services,
         Assembly[] assemblies,
         ServiceLifetime lifetime = ServiceLifetime.Scoped)
     {
@@ -108,5 +108,7 @@ private static void RegisterAllImplementationsOf<TInterface>(this IServiceCollec
                 }
             }
         }
+
+        return services;
     }
 }