feat: upgrade to MongoDB Node.js driver 4.x for MongoDB 5.0 support (#7794)

BREAKING CHANGE: The MongoDB GridStore adapter has been removed. By default, Parse Server already uses GridFS, so if you do not manually use the GridStore adapter, you can ignore this change.

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -479,6 +479,7 @@ export class MongoStorageAdapter implements StorageAdapter {
     const mongoObject = parseObjectToMongoObjectForCreate(className, object, schema);
     return this._adaptiveCollection(className)
       .then(collection => collection.insertOne(mongoObject, transactionalSession))
+      .then(() => ({ ops: [mongoObject] }))
       .catch(error => {
         if (error.code === 11000) {
           // Duplicate value
@@ -517,8 +518,8 @@ export class MongoStorageAdapter implements StorageAdapter {
       })
       .catch(err => this.handleError(err))
       .then(
-        ({ result }) => {
-          if (result.n === 0) {
+        ({ deletedCount }) => {
+          if (deletedCount === 0) {
             throw new Parse.Error(Parse.Error.OBJECT_NOT_FOUND, 'Object not found.');
           }
           return Promise.resolve();