Implement Prose test 13 from latest master (https://github.com/mongodb/specifications/blob/master/source/client-side-encryption/tests/README.rst#13-unique-index-on-keyaltnames)

Acceptance Criteria

• Both cases of FLE prose test 13 should pass in the Node driver

Since this work implements the tests from the latest master in the specs repo, this work should also cover a follow up ticket that was filed related to the prose tests (https://jira.mongodb.org/browse/NODE-4314).  We should double check that this work is completed as well.