ospfd: fix show ospf neigh json for multile nbrs

ospfd: fix show ospf neigh json for multile nbrs

Same neighbor learned from multiple ospf interfaces
(all) were not displayed in json, only last was displayed.
Created list within dictionary using neighbor-id as key.
lookup neigbhor-id in json obejct prior to creating new list.

spine-2# show ip ospf neighbor

Neighbor ID   Pri State     Dead Time Address     Interface
0.0.1.16        1 Full/DR   36.754s   8.0.3.15    swp1:8.0.3.16
0.0.1.16        1 Full/DR   30.903s   7.0.3.15    swp2:7.0.3.16

spine-2# show ip ospf neighbor json
{
   "0.0.1.16":[
   {
      "priority":1,
         "state":"Full\/DR",
         "deadTimeMsecs":35114,
         "address":"8.0.3.15",
         "ifaceName":"swp1:8.0.3.16",
         "retransmitCounter":0,
         "requestCounter":0,
         "dbSummaryCounter":0
   },
   {
      "priority":1,
      "state":"Full\/DR",
      "deadTimeMsecs":39264,
      "address":"7.0.3.15",
      "ifaceName":"swp2:7.0.3.16",
      "retransmitCounter":0,
      "requestCounter":0,
      "dbSummaryCounter":0
   }
   ]
}

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>