Issue Description

Exactly in this commit mongodb stopped exporting a Cursor object.

Because of that, every reference to ParentCursor.Prototype in MongoEntityManager (like here) is failing with error "Cannot read property 'prototype' of undefined".

Expected Behavior

No error expected.

Actual Behavior

Error "Cannot read property 'prototype' of undefined"

TypeError: Cannot read property 'prototype' of undefined
    at FindCursor.cursor.toArray (/entity-manager/MongoEntityManager.ts:679:37)
    at MongoEntityManager.<anonymous> (/entity-manager/MongoEntityManager.ts:97:23)
    at step (/node_modules/tslib/tslib.js:143:27)
    at Object.next (/node_modules/tslib/tslib.js:124:57)
    at fulfilled (/node_modules/tslib/tslib.js:114:62)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)

Steps to Reproduce

1. Add typeorm dependency
2. Add mongodb v4 dependency.

My Environment

Additional Context

Relevant Database Driver(s)

• aurora-data-api
• aurora-data-api-pg
• better-sqlite3
• cockroachdb
• cordova
• expo
• mongodb
• mysql
• nativescript
• oracle
• postgres
• react-native
• sap
• sqlite
• sqlite-abstract
• sqljs
• sqlserver

Are you willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time, and I know how to start.
• Yes, I have the time, but I don't know how to start. I would need guidance.
• No, I don't have the time, although I believe I could do it if I had the time...
• No, I don't have the time and I wouldn't even know how to start.