ldpd: add more filtering options in some "show" commands

ldpd: add more filtering options in some "show" commands

Being able to filter the output of some "show" commands is super useful
when troubleshooting large MPLS networks.

Examples:

% show mpls ldp ipv4 binding 10.0.0.48/29 longer-prefixes neighbor 192.168.0.5
AF   Destination          Nexthop         Local Label Remote Label  In Use
ipv4 10.0.0.48/30         192.168.0.5     24          26                no
ipv4 10.0.0.52/30         192.168.0.5     25          27                no

% show mpls ldp ipv4 binding 10.0.0.48/29 longer-prefixes neighbor 192.168.0.5 detail json
{
  "10.0.0.48\/30":{
    "localLabel":"24",
    "advertisedTo":[
      {
        "neighborId":"192.168.0.5"
      }
    ],
    "remoteLabels":[
      {
        "neighborId":"192.168.0.5",
        "label":"26",
        "inUse":0
      }
    ]
  },
  "10.0.0.52\/30":{
    "localLabel":"25",
    "advertisedTo":[
      {
        "neighborId":"192.168.0.5"
      }
    ],
    "remoteLabels":[
      {
        "neighborId":"192.168.0.5",
        "label":"27",
        "inUse":0
      }
    ]
  }
}

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>