tailcfg,all: add/plumb Node.IsJailed

This adds a new bool that can be sent down from control
to do jailing on the client side. Previously this would
only be done from control by modifying the packet filter
we sent down to clients. This would result in a lot of
additional work/CPU on control, we could instead just
do this on the client. This has always been a TODO which
we keep putting off, might as well do it now.

Updates tailscale/corp#19623

Signed-off-by: Maisem Ali <maisem@tailscale.com>

wgengine/wgcfg/nmcfg/nmcfg.go

@@ -110,6 +110,7 @@ func WGCfg(nm *netmap.NetworkMap, logf logger.Logf, flags netmap.WGConfigFlags,
 		didExitNodeWarn := false
 		cpeer.V4MasqAddr = peer.SelfNodeV4MasqAddrForThisPeer()
 		cpeer.V6MasqAddr = peer.SelfNodeV6MasqAddrForThisPeer()
+		cpeer.IsJailed = peer.IsJailed()
 		for i := range peer.AllowedIPs().Len() {
 			allowedIP := peer.AllowedIPs().At(i)
 			if allowedIP.Bits() == 0 && peer.StableID() != exitNode {