Update InitialDnsSeedlistDiscoveryTest

[jyemin]

JAVA-4532

This is harder to read than I thought it would be, probably because I tried to do a few things at the same time:

1. Refactor the test class so that it's a single test instead of multiple tests. This matches the spec test description more closely
2. Pull out a couple of methods that do the bulk of the assertions
3. Add parsed_options assertions
4. Support ping field in tests

If it's too hard to read I can split it up. Let me know.

[stIncMale]

Why do we have two effectively separate implementations of the test runner (assertErrorCondition, assertNonErrorCondition)? Intuitively, I'd expect that there is a single implementation that ignores some failures of some operations when isError, and fails otherwise.

[jyemin]

It just works out that way from following the logic of the test runner specification, which says:

If error is specified and true, drivers MUST verify that initializing the MongoClient throws an error. If error is not specified or is false, both initializing the MongoClient and running a ping operation must succeed without throwing any errors.

None of the assertions required for the non-error case are applicable for the error case, and vice versa.