Add blake3-hashseq codec (#347)

It is used for collections in iroh. For more information see https://iroh.computer/docs/layers/blobs#collections (resp. https://github.com/n0-computer/iroh.computer/blob/030f0b8104898327ca172ed5d1d84479d83208ad/src/app/docs/layers/blobs/page.mdx#collections).

table.csv

@@ -48,6 +48,7 @@ libp2p-key,                     ipld,           0x72,           permanent,  Libp
 git-raw,                        ipld,           0x78,           permanent,  Raw Git object
 torrent-info,                   ipld,           0x7b,           draft,      Torrent file info field (bencoded)
 torrent-file,                   ipld,           0x7c,           draft,      Torrent file (bencoded)
+blake3-hashseq,                 ipld,           0x80,           draft,      BLAKE3 hash sequence - per Iroh collections spec
 leofcoin-block,                 ipld,           0x81,           draft,      Leofcoin Block
 leofcoin-tx,                    ipld,           0x82,           draft,      Leofcoin Transaction
 leofcoin-pr,                    ipld,           0x83,           draft,      Leofcoin Peer Reputation