MDL-40047 events: Add events related to feedback responses

Adding following events related to feedback responses:-
/mod_feedback/event/response_deleted
/mod_feedback/event/response_submitted
/mod_feedback/event/instances_list_viewed
/mod_feedback/event/course_module_viewed
MDL-40047 feedback: Add a test generator for feedback
MDL-40047 events: Add unit tests for feedback events
MDL-40047 events: Replace add_to_logs with new events in feedback