Add more user interaction while configuring the TOTP

The user is now obligated to provide the TOTP value to continue. If not
provided, the user can still re-open the current page to get help or
retry the configuration process. This should remove the miss configured
account by not reading the configuration dialog (the user has to provide
at least once the TOTP to be able to finish the configuration; if the
TOTP value is set in the database, the configuration has been done at
least once).