With MR being moved to aggregation, result order can sometimes be different than expected. This adds a sort function before assertions to avoid test failures due to sorting.

Spec tests from mongodb/specifications@60adafcffa07174ac54c6e8658bd37a3faf350c3

Server versions < 3.4 do not support write concerns for drop commands. Rather than pass the context's write options directly to drop(), filter them through the Collection class so it can decide to inherit them based on the server's wire version.

Likewise for executing find() on the output collection.