Add Password Strength Meter to PasswordAuthenticator

Should be compliant with NIST 800-63B §5.1.1.2. ie:

Verifiers SHOULD offer guidance to the subscriber, such as a password-strength meter, to assist the user in choosing a strong memorized secret. This is particularly important following the rejection of a memorized secret on the above list as it discourages trivial modification of listed (and likely very weak) memorized secrets.