Enable splitting a test suite across multiple containers using "split by timings" CircleCI feature

[mileslane]

🦄 Feature Request

Is your feature request related to a problem?

I would like to be able to run our test suite on CircleCI and use the "split-by=timings" feature.

Describe the solution you'd like

This requires the output from the test run to include timing information so that, after an initial successful test pass, the tests can be split up across a set of containers and run in parallel. I not found any documentation so far that indicates this can be done currently.
https://circleci.com/blog/a-guide-to-test-splitting/
https://circleci.com/docs/2.0/parallelism-faster-jobs/#other-ways-to-split-tests