No Configuration Options for Access-Control-Allow-Private-Network

[ojasggg]

No 'Access-Control-Allow-Private-Network' header was present in the preflight response for this private network request targeting the local address space
The Above error occurs but can be easily solved if using middleware where the response header containing Access-Control-Allow-Private-Network is kept true. Need a new configuration option for Access-Control-Allow-Private-Network too as we have for other response header options that CORS provides.

[dougwilson]

Duplicate of #236