feat(machine): add ACLFilter if ACL's are enabled.

This commit change the default behaviour and remove the notion of namespaces between the hosts. It allows all namespaces to be only filtered by the ACLs. This behavior is closer to tailsnet.

utils.go

@@ -212,6 +212,15 @@ func (h *Headscale) getUsedIPs() ([]netaddr.IP, error) {
 	return ips, nil
 }
 
+func containsString(ss []string, s string) bool {
+	for _, v := range ss {
+		if v == s {
+			return true
+		}
+	}
+	return false
+}
+
 func containsIPs(ips []netaddr.IP, ip netaddr.IP) bool {
 	for _, v := range ips {
 		if v == ip {