Feedback: rename configuration properties

[minond]

The Configuration object should take a clientId and an apiKey instead of a username and password:

// This:
const apiConfig = new Configuration({
  clientId: process.env.MX_CLIENT_ID,
  apiKey: process.env.MX_API_KEY,
})

// Instead of this:
const apiConfig = new Configuration({
  username: process.env.MX_CLIENT_ID,
  password: process.env.MX_API_KEY,
})