Add authenticatorDisplayName to Step 27 and Step 23 of the registration and authentication ceremonies respectively

[zacknewman]

#1880 added the optional item authenticatorDisplayName to Credential Record; however it was not added to Step 27 of the registration ceremony nor Step 23 of the authentication ceremony. Seeing how attestationObject and attestationClientDataJSON exist in Step 27, it would be nice to also add authenticatorDisplayName. Honestly, I was under the impression authenticatorDisplayName was only a credProps thing; had it existed in the ceremony criteria section for data to store, I don't think I would have made that mistake.

Something like below would be nice:

The new credential record MAY also include the following OPTIONAL contents:

attestationObject

  response.attestationObject.

attestationClientDataJSON

  response.clientDataJSON.

authenticatorDisplayName

  clientExtensionResults.credProps.authenticatorDisplayName or RP-provided value.

[timcappalli]

authenticatorDisplayName is likely going to be removed from the spec. But if it stays, this is valid.

[zacknewman]

authenticatorDisplayName is likely going to be removed from the spec. But if it stays, this is valid.

Really? #2151 was just opened yesterday.

[emlun]

Even though credentialRecord/authenticatorDisplayName was added in #1880 along with credProps.authenticatorDisplayName, we should still recommend RPs to provide some way for users to set a "nickname" for their credentials, even if credProps.authenticatorDisplayName is deleted. So I think this is valid regardless of the outcome of that discussion.

Really? #2151 was just opened yesterday.

Yes, the sentiment in favour of dropping credProps.authenticatorDisplayName came up in discussions at TPAC shortly after #2151 was opened.