Currently, edx-platform interacts with Forum v2 via an HTTP (REST) API. But this protocol is no longer appropriate once the forum application is in the same Python runtime as edx-platform. Thus, forum v2 must expose a native Python API and calls to the forum HTTP client must be replaced. This means that in edx-platform, all calls to openedx.core.djangoapps.django_comment_common.comment_client.utils.perform_request must be replaced by a call to a corresponding forum.api.xxx function.
Forum v2 tests must also be migrated to accomodate for the new API.