fips_check_salts Rake task should detect BCrypt hashes

The fips_check_salts Rake task is meant to check for PBKDF2 hashed passwords with a salt that is too short to meet SP800-13.

If I understand correctly then if a customer is moving from non-FIPS where their user passwords are hashed with BCrypt to a FIPS environment, the guidance that they must reset their passwords is incorrect. On first sign-in the BCrypt password will be migrated to PBKDF2.

Thus, this Rake task should also detect BCrypt passwords and not display an error that the salt is too short.

There is a password_strategy method on the User model that will assist with detecting the password hash type.