Improvement: Set server origin as early as possible within the `server.start()` flow

[birdofpreyru]

To be moved up inside the function, just after the point the hostname and port are selected. https://github.com/birdofpreyru/react-native-static-server/blob/458348a3e3345542a6092b83654dc1f7a9094248/src/index.tsx#L285