Only get the last used security key to validate new users

The new api need the .hash() or .verify() to be clear regarding the specific operation done

Using one sequence per user type allow to have consecutiv numbering, removing the potential big gaps between users numbers and correlations data extraction (multiple accounts requested one after the other for one person will not imply anymore consecutive numbers)

Simple quote to double quote in the webauthn.js file

An encrypted value decrypted with the wrong password can produce non-sens output. By adding a prefix to the data, we can check if the decryption is done correctly or not