Add WaitUntilReadyOptions.serviceTypes() overload that accepts varargs

As a convenience, allow users to write:

waitUntilReadyOptions().serviceTypes(ServiceType.KV);

instead of:

waitUntilReadyOptions().serviceTypes(Set.of(ServiceType.KV));

Allow an empty set; interpret it as "wait for all possible" (just as if the method had not been called).