bgpd: fix add json attribute to reflect suppressed path

When aggregate is used, the suppressed information is not displayed in
the json attributes of a given path. To illustrate, the dump of the
192.168.2.1/32 path in the bgp_aggregate_address_topo1 topotest:

> # show bgp ipv4
> [..]
>  s> 192.168.2.1/32   10.0.0.2                               0 65001 i
>
> # show bgp ipv4 detail
> [..]
> BGP routing table entry for 192.168.2.1/32, version 17
> Paths: (1 available, best FRRouting#1, table default, vrf (null), Advertisements suppressed by an aggregate.)
>   Not advertised to any peer
>   65001            <---- missing suppressed flag
>     10.0.0.2 from 10.0.0.2 (10.254.254.3)
>       Origin IGP, valid, external, best (First path received)
>       Last update: Fri Jan 24 13:11:41 2025
>
> # show bgp ipv4 detail json
> [..]
> ,"192.168.2.1/32": [{"aspath":{"string":"65001","segments":[{"type":"as-sequence","list":[65001]}],"length":1},"origin":"IGP","valid":true,"version":17,
> "bestpath":{"overall":true,"selectionReason":"First path received"},                <---- missing suppressed flag
> "lastUpdate":{"epoch":1737720700,"string":"Fri Jan 24 13:11:40 2025\n"},
> "nexthops":[{"ip":"10.0.0.2","afi":"ipv4","metric":0,"accessible":true,"used":true}],
> "peer":{"peerId":"10.0.0.2","routerId":"10.254.254.3","type":"external"}}]

Fix this by adding the json information.

> # show bgp ipv4 detail
> [..]
> BGP routing table entry for 192.168.2.1/32, version 17
> Paths: (1 available, best FRRouting#1, table default, vrf (null), Advertisements suppressed by an aggregate.)
>   Not advertised to any peer
>   65001, (suppressed)
>     10.0.0.2 from 10.0.0.2 (10.254.254.3)
>       Origin IGP, valid, external, best (First path received)
>       Last update: Fri Jan 24 13:11:41 2025
>
> # show bgp ipv4 detail json
> [..]
> ,"192.168.2.1/32": [{"aspath":{"string":"65001","segments":[{"type":"as-sequence","list":[65001]}],"length":1},"suppressed":true,"origin":"IGP","valid":true,"version":17,
> "bestpath":{"overall":true,"selectionReason":"First path received"},
> "lastUpdate":{"epoch":1737720991,"string":"Fri Jan 24 13:16:31 2025"},
> "nexthops":[{"ip":"10.0.0.2","afi":"ipv4","metric":0,"accessible":true,"used":true}],"peer":{"peerId":"10.0.0.2","routerId":"10.254.254.3","type":"external"}}]

Signed-off-by: Philippe Guibert <[email protected]>

bgpd/bgp_route.c

@@ -10945,7 +10945,11 @@ void route_vty_out_detail(struct vty *vty, struct bgp *bgp, struct bgp_dest *bn,
 		else
 			vty_out(vty, ", (stale)");
 	}
-
+	if (bgp_path_suppressed(path)) { && json_paths)
+		if (json_paths)
+			json_object_boolean_true_add(json_path, "suppressed");
+		else vty_out(vty, ", (suppressed)");
+	}
 	if (CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_AGGREGATOR))) {
 		if (json_paths) {
 			json_object_int_add(json_path, "aggregatorAs",