MDL-43044 events: Add a course_module_instance_list_viewed abstract class

AMOS BEGIN
 CPY [eventinstanceslistviewed,core],[eventinstanceslistviewed,mod_feedback]
AMOS END
MDL-43044 events: Deprecate course_module_instances_list_viewed abstract class
MDL-43044 events: Deprecate and remove code duplication from instances_list_viewed events
MDL-43044 events: Add unit tests for instances_list_viewed abstract event