LDEV-3614: Improve processing of Gate activities. Alter lams_activity_learners table so it reflects its real purpose: storing learners who are allowed to pass a gate. Find out who is waiting in front of a gate using learner progress (activity attempt). For sync gate take into account all possible lesson learners (lesson class) rather than only ones who started a lesson. Use an entity in JSP generation rather than a DTO which is just a wrapper for the entity. Code clean up.