Support for JSON body (GraphQL support)

[instaatze]

I use this package for a Github integration in a React Native app. The authorization process was no problem. But when I tried to use the makeRequest function with the new Github GraphQL API I faced a problem: I need to send JSON in the request body. Looking at the Readme, there is no documented way to configure the request body. Looking at the code, I saw that you can pass a 'body' key with an object value in the options argument. But the keys of that object always seem to be appended as Multipart, and there is no way to define a Text or JSON body.

What I want to achieve is something like this:

  const response = await manager.makeRequest('github', 'https://api.github.com/graphql', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json; charset=utf-8',
      Accept: 'application/vnd.github.v4+json'
    },
    body: {
      query: 'query { viewer { login }}'
    }
  })

Or rather as a plain string:

  const response = await manager.makeRequest('github', 'https://api.github.com/graphql', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json; charset=utf-8',
      Accept: 'application/vnd.github.v4+json'
    },
    body: '{query: \'query { viewer { login }}\'}'
  })