b9c64db Add NODE_P2P_V2 to filters (Sjors Provoost)

Pull request description:

  Perhaps premature since bitcoin/bitcoin#24545 hasn't been merged yet, but I figured it would be handy if at least one seed supports it. Mine does now, only on mainnet:

  * `xc08.seed.bitcoin.sprovoost.nl` all SegWit enabled nodes including pruned ones
  * `x809.seed.bitcoin.sprovoost.nl` all SegWit enabled full archive nodes (needed for IBD)
  * for compact filters use `x849` for full archive nodes (or `xc48`, but Bitcoin Core only serves these filters on pruned nodes if they've been enabled since IBD, see bitcoin/bitcoin#21726)

  So far it's found one reachable node on IPv4.

  Usage (IPv4 vs IPv6, results under `ANSWER SECTION`):

  ```
  dig -t A xc08.seed.bitcoin.sprovoost.nl
  dig -t AAAA xc08.seed.bitcoin.sprovoost.nl
  ```

  Assuming modern node software won't need pre-segwit peers or bloom filters, these combinations have been omitted.

  Someone should sanity check the hex values.

ACKs for top commit:
  sipa:
    ACK b9c64db

Tree-SHA512: f6f8525e3ad997a2500a2b5f83273a328af53ddbd277c48dc7ea04f8a676189c1143cccb162c9e74a0ae7c3108996fa5acfd9472b8b58b1a64bb0c3b9eafa312