Log captcha attempts in the ACP

Ticket to follow-up this idea: https://www.phpbb.com/community/viewtopic.php?f=436&t=2649826

Add the ability for admins to log captcha attempts (whether successful or not) in the Admin Control Panel next to the other four log types (admin, mod, user and error logs). Each logged attempt should save the following information (similar to existing logs):

• Username (or anonymous)
• IP address
• Date & time
• The question presented with captcha type (qa or gdimg etc)
• The answer given by the user

Whatever the implementation, events should be present to allow extension developers to extend beyond this functionality to allow for various automations or filtering and such.