Add ipns record support

[laurentsenta]

ipns record in tests:

ipnsRecord := ipns.MustOpenRecord("t0124/key1.ipns-record")

ipnsRecord.TTL() // used to validate the cache output from API
ipnsRecord.Verify(bytes) // used to validate the output from API
ipnsRecord.Name() // used to contruct /ipfs/NAME

Also add means to check the Body output:
https://github.com/ipfs/kubo/blob/master/test/sharness/t0124-gateway-ipns-record.sh

ipns record during provision

• export the records
• use them during CI testing

[laurentsenta]

https://specs.ipfs.tech/ipns/ipns-record/#ipns-record

the public key might not live in the record:

If public key is small enough to fit in IPNS name (e.g., Ed25519 keys inlined using identity multihash), IpnsEntry.pubKey field is redundant and may be skipped to save space.

Which means we need to move around the public key / ipns name along with the record. File name is fine, but how do you store a record for an invalid key?

• [key]_suffix.ipns-record?
• or just move in a .yml file like we do currently with dnslink?

[laurentsenta]

• At the moment, when I open an ipns record, the PublicKey is equal to "m", why?

[laurentsenta]

• follow-up task: once we have ported the sharness tests, take some time to discuss what we need from ipns records
  • embed them in a car file served by a cargateway?
  • do we want to keep invalid ipns records?
  • how to store & use them in a way that is easier to maintain (right now the name has to contain the peerId)

[laurentsenta]

Complete, see the PR for discussion about car serving, etc.