Add new filter to abort/prevent notification based on notification or post id/data

[olatechpro]

Add new filter to abort/prevent notification based on notification or post id/data.

Sample Usage:

add_action( 'publishpress_notifications_schedule_notification', 'conditionally_abort_pp_notification', 10, 2 );
add_action( 'publishpress_notifications_send_notification', 'conditionally_abort_pp_notification', 10, 2 );
function conditionally_abort_pp_notification($send_notification, $workflow) {
    if ($workflow) {
        //This is is the notification ID. This can be used to limit the check to specific notification
        $workflow_id = $workflow->workflow_post->ID;
        //This is the current post id for which the notification is been sent/scheduled for.
        $post_id = $workflow->event_args['params']['post_id'];

        // check if post has specific meta with specific value
        $post_meta_value = get_post_meta($post_id, 'research', true);

        if ($post_meta_value !== 'AAA') {
            // don't send the notification if research meta key value is not equals AAA
            $send_notification = false;
        }
    }
    return $send_notification;
}