Expand GeodeAwaitility so that the default timeout can be used for Mockito.timeout

Many tests use Mockito.verify which supports Mockito.timeout. I'd like to expose the timeout in GeodeAwaitility for use with Mockito.timeout. I'd also like to add toTimeDuration to facilitate conversions between java.time.Duration and org.awaitility.Duration.

Since GeodeAwaitility does not have any unit tests, we should also make it testable.