Split server code into API server and HTTP server for server-side rendering

[larixer]

GraphQL API server and HTTP server for SSR should be split into separate packages for clarity and greater flexibility. We should also remove imports from the server code to client code, for example importing all client modules is not efficient, since we essentially have two passes of compilation, one pass for packages/client and another pass for packages/server. Instead we should import client bundle from build folder during production, or load client bundle from webpack dev server during development if client bundle has been changed