Comment approval/type check runs after `notify_post_author` filter

[adamsilverstein]

The notify_post_author filter "Filters whether to send the post author new comment notification emails, overriding the site setting.". However the current code performs two logic checks after the filter - before actually sending the notification. Notifications are only sent if the comment type is a note, or the comment is approved. notifications are not sent for unapproved comments, even when notify_post_author returns true.

Therefore, it makes sense to move these logic checks _before_ the filter which would give developers core complete control over notifications.

Trac ticket: https://core.trac.wordpress.org/ticket/64217