Feature
* feat(graphql): allow passing context_value for testing
Problem
=======
`graphql` extension does not allow to pass a custom context value when
doing `service.schema.execute()`. One use case is to pass a request
with headers to test the authentication logic.
Solution
========
An optional context_value is now accepted as argument to
`schema.execute` and `schema.subscribe`.
Note
====
The `http` module now also exports `litestar.Request` and
`litestar.testing.RequestFactory`, useful when writing tests. ([`5d2c12e`](https://github.com/betaboon/aio-microservice/commit/5d2c12ea71ad3ab7e66e6668527aed174bea8c76))