[Merged by Bors] - feat: Added materialization for testcase components

[dcramer]

• Materialize first_build_id on TestCaseMeta
• Add date_created to TestCase to improve pulling test history

This will need to be followed up with:

1) A backfill on TestCaseMeta 2) A backfill/corrrection on TestCase.date_created for historical rows

[dcramer]

migrations might not actually run in prod - will address if deploys fail

bors r+

[bors[bot]]

Pull request successfully merged into master.

Build succeeded:

• continuous-integration/travis-ci/push