Rewrapped function with C++14 and repackaged with VS2022

[GsoyG]

• Encapsulate the main functions into the DHCPServer class and the message structure into the DHCPMessage class.
• Split the output into main.cpp and replace the original error output with exceptions.
• Replaced the original macro definition with static member functions and constant expressions.
• Put the else judgment of if in front to simplify the if hierarchy.
• Removed LocalFree check.

[DavidAnson]

This is very interesting, but I'm not in a place to review or test changes to this project. Sorry! Looking at how much you've invested, maybe you would like to maintain a fork of the project?

[GsoyG]

Thank you very much for your reply.
I am a C++ beginner, this is my first time creating a pull request to a public repository, and I am not very familiar with these operations.
I needed to use the DHCP function in one of my gadgets, so I found this repository. But these codes seemed to be written in C style, so I modified them in C++ style according to my ideas.
I thought this code might be helpful to someone, so I tried creating a pull request.