[Shared Tasks] Enforce task reqs on player removal (#2342)

This verifies a shared task's minimum players requirement is still met
when a member is removed and schedules it for termination if not

common/shared_tasks.h

@@ -2,6 +2,7 @@
 #define EQEMU_SHARED_TASKS_H
 
 #include "database.h"
+#include "timer.h"
 #include "types.h"
 #include "repositories/character_data_repository.h"
 #include "repositories/tasks_repository.h"
@@ -203,6 +204,8 @@ public:
 	std::vector<uint32_t>                     member_id_history; // past and present members for replay timers
 	std::vector<uint32_t>                     dynamic_zone_ids;
 
+	Timer terminate_timer;
+
 protected:
 	SharedTasksRepository::SharedTasks m_db_shared_task;