Users of CSOT will possibly encounter three errors: context.DeadlineExceeded from client-side timeouts of contexts created to honor the new Timeout option, driver.ErrDeadlineWouldBeExceeded for operations that will probably not complete a round-trip in time given the deadline of their context, and server-side errors from maxTimeMS. All three of these errors represent a similar underlying situation: Timeout is too low for the given operation. We need to decide how to hand these errors back to users.

Also sync CSOT errors spec tests.