New feature: republishing of an existing ipns-record

[agmap]

sending a PUT of an existing ipns-record file to /routing/v1/ipns/{name} for republishing.

[2color]

I looked into this, and this is a little tricky for two reasons:

1. Importing a record is pretty easy. The problem the public key is not always included in the IPNS record (as per spec https://specs.ipfs.tech/ipns/ipns-record/#public-key-bytes since its typically inlined in the name for ed25519). So the ipns-record file is not enough and you need to pass the name too. The public key is important, because we derive the name from it and also use it to determine the DHT routing key.
2. @helia/ipns doesn't have an API for republishing just a record. I opened Add ability to republish IPNS records without private key ipfs/helia#744 for this

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How to we resolve 1:

1. Embed the public key when creating the record. This will only fix this for records created with the inspector.
2. Require the user to also pass the pubkey/name would make the UI more complicated,

[agmap]

Take the PublicKey from the filename of the ipns-record file. It’s always included when I download it with the browser from https://delegated-ipfs.dev/routing/v1/ipns/k5..........gk6r