tor: Change auth order to only use HASHEDPASSWORD if -torpassword

Change authentication order to make it more clear (see #7700).

• If the -torpassword option is provided, force use of HASHEDPASSWORD auth.

• Give error message if -torpassword provided, but HASHEDPASSWORD auth is not available.

• Give error message if only HASHEDPASSWORD available, but -torpassword not given.