CDRIVER-4000 Test redaction of sensitive commands (#814)

* Sync command monitoring spec tests

This brings the spec tests up to date with mongodb/specifications#84ac002b

* Add support for 1.5 unified test format schema

This adds support for the "observeSensitiveCommands" monitoring option, as well as the new "auth" runOnRequirement.

* Redact sensitive commands for APM

* Test redaction of replies for sensitive commands

* Force redaction of replies for sensitive commands

Previously, the driver would not redact the reply to a hello command with speculative authentication unless the reply also was sensitive. As this makes the test completely useless, we've decided to always require redaction of replies when the command was redacted.

* Document is_redacted and force_redaction arguments to APM initialisers

* Make redaction helpers static