WatchTowerHQ < 3.10.4 - Authentication Bypass to Administrator due to Missing Empty Value Check

Description

The plugin is vulnerable to authentication bypass due to the 'watchtower_ota_token' default value is empty, and the not empty check is missing in the 'Password_Less_Access::login' function. This makes it possible for unauthenticated attackers to log in to the WatchTowerHQ client administrator user.