MDL-39959 events: Add course module events

Added event course_module_created
Added event course_module_updated
Added event course_module_deleted
MDL-39959 events: Add unit tests for course module events

test_course_module_created_event()
test_course_module_created_event_exceptions()
test_course_module_updated_event()
test_course_module_updated_event_exceptions()
test_course_module_deleted_event()
test_course_module_deleted_event_exceptions()
Replace add_to_log() calls with events for course module actions (create, delete and update)