Add entry point that mocks global MongoDB

[LinusU]

Currently we are using something like this to test our API with a mocked version of MongoDB, without having to specifically having to code the app to know anything about Mongo Mock:

const mock = require('mongo-mock')
const real = require('mongodb')

mock.max_delay = 0
real.MongoClient = mock.MongoClient
real.ObjectId = mock.ObjectId

I think that it could be a benefit to add this as an entry point to this package, the same way that e.g. dotenv/config works. Providing this instead of letting every end users write their own has some benefits:

• Easy to run any MongoDB app with node -r mongo-mock/global app.js
• End user doesn't need to figure out which properties needs patching
• Works even if the end user uses ESM