tools: ynltool: add page-pool stats

tools: ynltool: add page-pool stats

Replace the page-pool sample with page pool support in ynltool.

 # ynltool page-pool stats
    eth0[2]	page pools: 18 (zombies: 0)
		refs: 171456 bytes: 702283776 (refs: 0 bytes: 0)
		recycling: 97.3% (alloc: 2679:6134966 recycle: 1250981:4719386)
 # ynltool -j page-pool stats | jq
 [
  {
    "ifname": "eth0",
    "ifindex": 2,
    "page_pools": 18,
    "zombies": 0,
    "live": {
      "refs": 171456,
      "bytes": 702283776
    },
    "zombie": {
      "refs": 0,
      "bytes": 0
    },
    "recycling_pct": 97.2746,
    "alloc": {
      "slow": 2679,
      "fast": 6135029
    },
    "recycle": {
      "ring": 1250997,
      "cache": 4719432
    }
  }
 ]

 # ynltool page-pool stats group-by pp
 pool id: 108  dev: eth0[2]  napi: 530
   inflight: 9472 pages 38797312 bytes
   recycling: 95.5% (alloc: 148:208379 recycle: 45386:153842)
 pool id: 107  dev: eth0[2]  napi: 529
   inflight: 9408 pages 38535168 bytes
   recycling: 94.9% (alloc: 147:180178 recycle: 42251:128808)

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20251107162227.980672-3-kuba@kernel.org
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>