T2898: add ndp-proxy service

VyOS CLI command
  set service ndp-proxy interface eth0 prefix 2001:db8::/64 mode 'static'

Will generate the following NDP proxy configuration

  $ cat /run/ndppd/ndppd.conf
  # autogenerated by service_ndp-proxy.py

  # This tells 'ndppd' how often to reload the route file /proc/net/ipv6_route
  route-ttl 30000

  # This sets up a listener, that will listen for any Neighbor Solicitation
  # messages, and respond to them according to a set of rules
  proxy eth0 {
      # Turn on or off the router flag for Neighbor Advertisements
      router no
      # Control how long to wait for a Neighbor Advertisment message before invalidating the entry (milliseconds)
      timeout 500
      # Control how long a valid or invalid entry remains in the cache (milliseconds)
      ttl 30000

      # This is a rule that the target address is to match against. If no netmask
      # is provided, /128 is assumed. You may have several rule sections, and the
      # addresses may or may not overlap.
      rule 2001:db8::/64 {
          static
      }
  }

1 files changed, 1 insertions, 0 deletions

diff --git a/data/configd-include.json b/data/configd-include.json
index 92d3863ce..6d7261b73 100644
--- a/data/configd-include.json
+++ b/data/configd-include.json
@@ -63,6 +63,7 @@
 "service_ipoe-server.py",
 "service_mdns-repeater.py",
 "service_monitoring_telegraf.py",
+"service_ndp-proxy.py",
 "service_pppoe-server.py",
 "service_router-advert.py",
 "service_upnp.py",