BREAKING CHANGE: camelCase remaining file names

Fix #13308

Author: vkarpov15

lib/aggregate.js

@@ -4,7 +4,7 @@
  * Module dependencies
  */
 
-const AggregationCursor = require('./cursor/AggregationCursor');
+const AggregationCursor = require('./cursor/aggregationCursor');
 const MongooseError = require('./error/mongooseError');
 const Query = require('./query');
 const { applyGlobalMaxTimeMS, applyGlobalDiskUse } = require('./helpers/query/applyGlobalOption');

lib/connection.js

@@ -4,7 +4,7 @@
  * Module dependencies.
  */
 
-const ChangeStream = require('./cursor/ChangeStream');
+const ChangeStream = require('./cursor/changeStream');
 const EventEmitter = require('events').EventEmitter;
 const Schema = require('./schema');
 const STATES = require('./connectionState');