[CENNSO-920] feat: binapi for nat pool

[ivan4th]

Need an API call for listing the NAT pools as well, like it is done for the UE IP pools. Any problems with just iterating using something like the following for it? (looking at the vnet_upf_nat_pool_add_del function)

  upf_main_t *sm = &upf_main;
  upf_nat_pool_t *nat_pool;
  ...
  pool_foreach(nat_pool, s->nat_pools)
  {
    ...
  }