Managing target processes (destinations on same machine)

[HttpPlattformHandler](https://docs.microsoft.com/en-us/iis/extensions/httpplatformhandler/httpplatformhandler-configuration-reference) in IIS is used to start external processes and proxy requests to it. It was the base for the IIS Integration of ASP.NET Core (ASP.NET Core-Modul).

### What should we add or change to make your life better?
Add functionality to open/manage a TCP Sockets and for child processes to listen on.

As platform-independent handling of TCP Sockets is rather error prone and probably the passing of a socket from parent to child process even more so (WSADuplicateSocket anyone?) it would be nice to have this oob.

I'm perfectly aware that process handling (start/stop) is probably out of scope, but the TCP Sockets stuff would help quite a lot.

### Why is this important to you?
- Being able to start/run an external process and proxy requests to it with a single consistent solution (e.g. not use IIS on Windows and NGINX on Linux etc.).
- Reduce size of possible container scenarios (Windows Nano container instead of Core)
- More possibilities to influence requests (add/remove headers etc.)