net: change ConnectSocketDirectly() to take a Sock argument

Change `ConnectSocketDirectly()` to take a `Sock` argument instead of a
bare `SOCKET`. With this, use the `Sock`'s (possibly mocked) methods
`Connect()`, `Wait()` and `GetSockOpt()` instead of calling the OS
functions directly.

src/i2p.cpp

@@ -279,7 +279,7 @@ Sock Session::Hello() const
         throw std::runtime_error("Cannot create socket");
     }
 
-    if (!ConnectSocketDirectly(m_control_host, sock->Get(), nConnectTimeout, true)) {
+    if (!ConnectSocketDirectly(m_control_host, *sock, nConnectTimeout, true)) {
         throw std::runtime_error(strprintf("Cannot connect to %s", m_control_host.ToString()));
     }