Register multibase values to identify ML-DSA-44 keys

[wip-abramson]

The Multikey encoding of a ML-DSA public key MUST start with the two-byte prefix 0x8724 (the varint expression of 0x1207) .

Is there a value to identify a private key also?

Reminder that we /really/ need to register these values here: https://github.com/multiformats/multicodec/blob/master/table.csv#L168