Update the jstest.py and fixture.py interface

The mongo shell that gets created as part of jstest.py should be aware of fixtures since shell-spawned fixtures need a lot of the configuration passed into fixture.py

Right now a lot of the options for shell fixtures are done ad-hoc and mostly directly by accessing properties on the global config object, this is hard to test, and hard for someone to modify correctly if they're making a change to a fixture.

We should formalize resmoke's fixture config object, likely under fixturelib, and pass it to jstest.py for the shell's consumption, replacing current shell fixture options.

Considerations

• Try to upfront testing locally before patches by copying over the TestData the shell sets in Evergreen for a variety of tasks and checking those options are consistent with runs locally.
• Add unittests for the above that asserts values on the final testData object.