From the spec:

Drivers MUST raise an error when attempting to auto encrypt a command if the maxWireVersion is less than 8.

https://github.com/mongodb/specifications/blob/master/source/client-side-encryption/client-side-encryption.rst#auto-encrypt-and-decrypt

Should we also raise an error when the current operation does not use OP_MSG? For example exhaust cursors, find_raw_batches, etc...?