svcutil generating incorrect client for WSHttpBinding with SecurityMode.TransportWithMessageCredential

Defining a WCF Core service using WSHttpBinding with SecurityMode.TransportWithMessageCredential. Creating a client using .NET Framework, will correctly be able to call the service.

The generated code for a .NET core client does not, and fails.

The service endpoint is defined using:

``` c#
public void Configure(IApplicationBuilder app)
{
var wsHttpBindingWithCredential = new WSHttpBinding(SecurityMode.TransportWithMessageCredential);
wsHttpBindingWithCredential.Security.Message.ClientCredentialType = MessageCredentialType.UserName;

app.UseServiceModel(builder =>
{
// Add the Echo Service
builder.AddService(serviceOptions =>
{
// Set a base address for all bindings to the service, and WSDL discovery
serviceOptions.BaseAddresses.Add(new Uri($"http://localhost:{Program.HTTP_PORT}/EchoService"));
serviceOptions.BaseAddresses.Add(new Uri($"https://localhost:{Program.HTTPS_PORT}/EchoService"));
})
// Add WSHttpBinding endpoints
.AddServiceEndpoint(new WSHttpBinding(SecurityMode.None), "/wsHttp")
.AddServiceEndpoint(new WSHttpBinding(SecurityMode.Transport), "/wsHttp")
.AddServiceEndpoint(wsHttpBindingWithCredential, "/wsHttpUserPassword", ep => { ep.Name = "AuthenticatedEP"; });

builder.ConfigureServiceHostBase(CustomUserNamePasswordValidator.AddToHost);

// Configure WSDL to be available over http & https
var serviceMetadataBehavior = app.ApplicationServices.GetRequiredService();
serviceMetadataBehavior.HttpGetEnabled = serviceMetadataBehavior.HttpsGetEnabled = true;
});
}
```

The `GetBindingForEndpoint` generated code for the service definition is:

``` c#
if ((endpointConfiguration == EndpointConfiguration.AuthenticatedEP))
{
System.ServiceModel.Channels.CustomBinding result = new System.ServiceModel.Channels.CustomBinding();
System.ServiceModel.Channels.TransportSecurityBindingElement userNameOverTransportSecurityBindingElement = System.ServiceModel.Channels.SecurityBindingElement.CreateUserNameOverTransportBindingElement();
userNameOverTransportSecurityBindingElement.MessageSecurityVersion = System.ServiceModel.MessageSecurityVersion.WSSecurity11WSTrustFebruary2005WSSecureConversationFebruary2005WSSecurityPolicy11BasicSecurityProfile10;
result.Elements.Add(userNameOverTransportSecurityBindingElement);
System.ServiceModel.Channels.TextMessageEncodingBindingElement textBindingElement = new System.ServiceModel.Channels.TextMessageEncodingBindingElement();
result.Elements.Add(textBindingElement);
System.ServiceModel.Channels.HttpsTransportBindingElement httpsBindingElement = new System.ServiceModel.Channels.HttpsTransportBindingElement();
httpsBindingElement.AllowCookies = true;
httpsBindingElement.MaxBufferSize = int.MaxValue;
httpsBindingElement.MaxReceivedMessageSize = int.MaxValue;
result.Elements.Add(httpsBindingElement);
return result;
}
```

Which is incorrectly trying to use CreateUserNameOverTransportBindingElement(); which is incorrect for this binding type.