Updated TypeScript typings

[Tenga]

This PR will update the TS typings, as they seem to have gone out of date with the 2.4 config changes.

I've made each property in each config optional, as from what I can tell, most of them have defaults and are not mandatory. It also allows the authors to pass in partial objects (file config with just attributes instead of forcing you to define tracks, forceAudio, etc.)

Each individual config for each video provider are also now their own exported interfaces so you can reuse the types without having to recreate them yourself in cases like this:

import ReactPlayer, { FileConfig, TrackProps } from "react-player";

// ...
const getTracks = (): TrackProps[] => {
  // Whatever get tracks does...
}

// ...
const fileConfig: FileConfig = {
  tracks: getTracks(),
}

// ...
<ReactPlayer config={{ file: fileConfig }} />

[cookpete]

Nice work 👍