Windows: Add support for handling protocol (netlink family)

Windows: Add support for handling protocol (netlink family)

Windows datapath currently has no notion of netlink family.
It assumes all netlink messages to belong to NETLINK_GENERIC family.
This patch adds support for handling other protocols if the userspace sends it down to kernel.

This patch introduces a new NETLINK_CMD - OVS_CTRL_CMD_SOCK_PROP to manage
all properties associated with a socket. The properties are passed down as
netlink message attributes. This makes it easier to introduce other
properties in the future.

Signed-off-by: Sairam Venugopal <vsairam@vmware.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Gurucharan Shetty <guru@ovn.org>