Fix decoding Attestation auth data with extentions

[RobHarveyDev]

Issue #, if available:

This fixes an issue similar to this one: cedarcode/webauthn-ruby#107

Samsung passkeys seem to pass an extension

{
    "hmac_secret": true
}

which is causing the cbor decoder to fail as there's more data than expected.

The error we are seeing in AWS Cloudwatch is:
Unexpected data: 0xa1 at decodeFirstSync (file:///var/task/index.mjs:1830:19) at cborDecode (file:///var/task/index.mjs:4541:44) at decodeCredentialPublicKey

This change decodes all the data to prevent this, and then returns the first decoded object to replicate the existing returned data.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[ottokruse]

So is this a bug in cbor or in our lib? Willing to accept your PR in either case, just curious

[RobHarveyDev]

I think it's a bug in the library as it's not expecting any additional data, such as the extensions.

[ottokruse]

Thx for the PR