Use golang.zx2c4.com/wireguard/windows/tunnel/winipcfg
instead of github.com/tailscale/winipcfg-go package.
Updates #760
Signed-off-by: Alex Brainman <alex.brainman@gmail.com>
Not used for anything yet (except logging), but populate the current
proxy autoconfig PAC URL in Interfaces.State.
A future change will do things based on it.
Also remove rebinding logic from the windows router. Magicsock will
instead rebind based on link change signals.
Signed-off-by: David Anderson <danderson@tailscale.com>