qemu 5.2.0: Add reconnect option support for netdev socket

Most of qemu socket accepting options (such as chardev) accept among other things a "reconnect" option.

netdev socket however returns: Invalid parameter 'reconnect'

It would make sense that available options for socket links be at least partially normalized (also see issue https://bugs.launchpad.net/qemu/+bug/1903470 which was closed without resolution).