cmd/tailscale,ipn,tailcfg: add tailscale advertise subcommand behind envknob (#13734)

Signed-off-by: Naman Sood <mail@nsood.in>

ipn/ipn_clone.go

@@ -27,6 +27,7 @@ func (src *Prefs) Clone() *Prefs {
 	*dst = *src
 	dst.AdvertiseTags = append(src.AdvertiseTags[:0:0], src.AdvertiseTags...)
 	dst.AdvertiseRoutes = append(src.AdvertiseRoutes[:0:0], src.AdvertiseRoutes...)
+	dst.AdvertiseServices = append(src.AdvertiseServices[:0:0], src.AdvertiseServices...)
 	if src.DriveShares != nil {
 		dst.DriveShares = make([]*drive.Share, len(src.DriveShares))
 		for i := range dst.DriveShares {
@@ -61,6 +62,7 @@ var _PrefsCloneNeedsRegeneration = Prefs(struct {
 	ForceDaemon            bool
 	Egg                    bool
 	AdvertiseRoutes        []netip.Prefix
+	AdvertiseServices      []string
 	NoSNAT                 bool
 	NoStatefulFiltering    opt.Bool
 	NetfilterMode          preftype.NetfilterMode