DRIVERS-1541 added KMS retries with backoff. However if the retries all fail then mongocrypt returns the following error:
> "KMS request failed after 3 retries due to a network error"

This is very vague and doesn't give any actionable information to the user. A common scenario might be that the kms tls options are incorrect. Do we need to change mongocrypt to accept an error message from the driver when a KMS request fails? That way it could include useful information about when the previous 3 attempts failed.

Alternatively we could have drivers track the errors and supplement the error message from mongocrypt.