Optizely instace with custom headers

[wellyal]

I should be able to send a custom header (eg Authorization) within the request considering the fact that I can point my instance to another endpoint which may need other kinds of information

const optimizely = createInstance({
    sdkKey: 'development',
    headers: { Authorization: "23984712348213g48b8sgd8f" } // suggestion
    datafileOptions: {
      urlTemplate: 'http://localhost:3001/optimizely/datafile/%s',
    },
  })

[Tamara-Barum]

Internal Ticket: [FSSDK-8655]