Implement "toArray" method for cursors and change streams

We should implement a public all method on cursors that is consistent between async and sync. We should also consider if it is worth implementing such a thing on change streams as well, mainly for the purposes of leveraging Sequence behavior on batches of events.

There is an existing internal implementation of the method that is currently used by the driver and in some tests, and it is not necessary to preserve this implementation after this ticket is resolved.