I currently have a use-case where I need to check if thrown error is a `BulkWriteError`. Right now, the only way I can import this is by importing it 'mongodb/lib/bulk/common', but I would like to be able to import it from 'mongodb'

Current behavior:

import { ClientSession, Collection, BulkWriteResult, WriteError } from 'mongodb' 
import { BulkWriteError } from 'mongodb/lib/bulk/common'

Desired behavior:

import { BulkWriteError, ClientSession, Collection, BulkWriteResult, WriteError } from 'mongodb'

Additionally, the typescript definitions for the Node.js driver are missing BulkWriteError. Once the Node.js driver exposes BulkWriteError in the root module, I can open a PR on the type definitions to add BulkWriteError.