Add support for combination testing

The SDK should implement the ability to pass the testing server version to its test invocation. This will allow the SDK to perform only the tests that are available to a particular server version and avoid tests for features which are not yet implemented. Should no version be passed, the SDK should either select a reasonable default (the current stable version), or attempt to perform heuristics to determine the cluster version (Note: there is ongoing work on a proposal for a common set of heuristics to do this).

See the linked CBD for further details.