add ability to customize Autogenerated Message

[dansiegel]

Description

Currently the output code includes an autogenerated header with a default Autogenerated message. This PR adds the ability to add a customized Autogenerated Message

var builder = CodeGenerate.Create("AwesomeApp")
                          .WithAutoGeneratedMessage(@"This file was autogenerated by my Code Generator
Copyright (c) 2022 My Company

Do not make changes to this file.");