Complete E2E tests of lib microservice

[prasadtalasila]

To achieve:

1. Write end-to-end (E2E) tests for library microservice and put them in top-level test/ directory.
2. Make this test work in lib-ms.yml github action.
3. Make the test work with traefik both on a developer computer and in github action.

Use supertest for testing HTTP form of requests and apollo graphql client for GraphQL requests.

[prasadtalasila]

The existing E2E tests of lib microservices fail with or without Traefik gateway. The reason for failure is the change in either the REST API or the GraphQL of Gitlab. The failure is not due to any new code introduced since release-v0.2. The code fails retrospectively for all the past releases of lib microservice as well.
PR #326 contains structural improvements to the end-to-end tests but the tests still fail.

[prasadtalasila]

The end-to-end tests have been completed without Traefik. The end-to-end tests of the full application will be taken up later.