Session Lookup should use indexes

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

There are no indexes created the _Session class. This means that the default index of _id is used when session tokens are looked up

Steps to reproduce

Create a new user.

Actual Outcome

No indexes are created. An index on _session_token could increase the performance of session lookups

Expected Outcome

Parse Server should use hint / indexes when looking up session tokens

Environment

Server

• Parse Server version: 5.3.0
• Operating system: macos
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): localhost

Database

• System (MongoDB or Postgres): mongo
• Database version: 5.0
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): atlas

Client

• SDK (iOS, Android, JavaScript, PHP, Unity, etc): js
• SDK version: 3.5.0

Logs

Start by tracing the Session Lookup path and the MongoDB setup for the _Session class. Check how session tokens are queried and which indexes are created or used. Done means session-token lookups use an appropriate index and the behavior is verified against the reported MongoDB case.