Add ServerSideSort control integration tests

[jsumners]

Using the apacheds image, https://github.com/ldapjs/docker-test-apacheds/pkgs/container/docker-test-apacheds/apacheds, we should add proper integration tests for the ServerSideSort control. These tests will verify that we are sending the sort control request correctly, and verify that we are parsing the returned sort control response correctly.

See https://github.com/ldapjs/docker-test-apacheds/tree/b5b4c6b3807674fa3490b37946bdb388e0cdc073#testing-the-vlv-control for an example.