Add application passwords support

[xipasduarte]

Add bypass support for application password. tsb-site-lock.php

Currently there is a model to bypass with defined keys on a constant, but WordPress has an application password feature, which is similar and allows the users' to control their own keys. We should support that and add a notice for the other model.

• Add application password support
• Add alert when constant exceptions are used under LOCK_BYPASS_KEYS