Metadata ctor is incorrect

[Drake53]

https://github.com/Drake53/CSharp.lua/issues/2

[yanghuan]

namespace Test {
  public class A {
    public A(int a, string b = null) {
    }
  }

  public class Program
  {
    private static void Main(string[] args)
    {
      Activator.CreateInstance(typeof(A),  100);
    }
  }
}

i run this code in .NET6, it also got a exception, so in lua it will also got a error

Unhandled exception. System.MissingMethodException: Constructor on type 'Test.A' not found.
   at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture)
   at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
   at System.Activator.CreateInstance(Type type, Object[] args)
   at Test.Program.Main(String[] args) in C:\Person\Project\code\cstolua\cstolua\src\Progrom.cs:line 20