net: socket options ignored before connect

[mscdex]

Currently if you try setting socket options (e.g. via socket.setKeepAlive()) on a new TCP socket before calling socket.connect(), the arguments are silently ignored.

To avoid confusion about this I suggest two separate solutions:

• Throw an error if no handle is created yet
• Save the arguments on the socket object for applying after a handle is created

[vkurchatkin]

related: #7077