Deeply nested keys are not passed correctly to afterSave triggers

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest version of Parse Server.

Issue Description

afterSave triggers do not receive the correct updated object, if a deeply nested key was updated.

Steps to reproduce

1. Create an afterSave trigger for a class
2. Create a document with a deeply nested key:

const obj = new Parse.Object('GameScore');
obj.set('a', {'b':{'c':0}});
await obj.save();

3. Change the deeply nested key

obj.set('a.b.c', 1);
await obj.save();

Actual Outcome

The afterSave triggers receives a wrong object (in request.object)

Expected Outcome

In the trigger call for the second save(), the field a of the received object should be {'b':{'c':1}}

Failing Test Case / Pull Request

• 🤩 I submitted a PR with a fix and a test case.
• 🧐 I submitted a PR with a failing test case.

Environment

Server

• Parse Server version: Latest commit as of 12 May 2021, 51e0800
• Operating system: any
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): local

Database

• System (MongoDB or Postgres): MongoDB
• Database version: v4.4.5
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): local

Client

• SDK (iOS, Android, JavaScript, PHP, Unity, etc): any
• SDK version: any

Logs

Reproduce the issue by saving an object with a deeply nested key, changing it with obj.set('a.b.c', 1), and saving again. Inspect the afterSave trigger's request.object and verify that a contains {'b':{'c':1}}; the issue body indicates that a fix and test case were already submitted.