Feature Request: Expose http handler via napi to nodejs

[aarne]

Current usage of @graphql-conductor/lib is strictly limited to running a single standalone server only

import conductor from '@graphql-conductor/lib'

conductor.executeConductor(configFilePath)

For many use-cases this is too limiting. We might want to also expose a lower level api

import conductor from '@graphql-conductor/lib'

const gw = conductor.createGateway(configObject)

const response = await gw.handle(req)

Motivation:

• running multiple graph variants in parallel (automatic environments for each branch in CI/CD for example). Each feature branch has a unique domain name based on which appropriate graph configuration is fetched.
• pre/post processing of user requests in nodejs (custom auth requirements etc)