init_beanie with mongo session instead of database instance

[resulyrt93]

Hey team,

We need to initialize beanie instance with mongodb session instead of database instance. Thus we can initialize a real mongodb instance in the tests and we want to use following approach for reuseability.

@pytest.fixture
def rollback_session(mongodb):
    session = mongodb.start_session()
    session.start_transaction()
    try:
        yield session
    finally:
        session.abort_transaction()

source: https://www.mongodb.com/developer/products/mongodb/pytest-fixtures-and-pypi/

I've used SessionMethods but it didn't work. Is there any workaround way to provide session instance globally? Setting the session in all .find(), .update() etc. operations causes big refactoring effort for now :(