I just went through all the types JSON types in @simplewebauthn/typescript-types and matched them against the latest L3 draft and almost everything looks good:

...Except for missing additions of the "convenience values" publicKeyAlgorithm, publicKey, and authenticatorData on AuthenticatorAttestationResponseJSON. These values come from the correspondingly-named get...() methods on AuthenticatorAttestationResponse.

The types deviate a bit from what's in L3 because 1) L3 isn't the Recommendation yet, and 2) browser compatibility is still a little spotty (MDN says Firefox doesn't really support the getters):

• getAuthenticatorData()
• getPublicKeyAlgorithm()
• getPublicKey()

This PR will return the values in the output from browser's startRegistration() when their corresponding getter methods are available.

Fixes #384.