e2e tests should not be running when `npm test` is invoked

[ericelliott]

because e2e tests are not testing only pure functions, they can have side-effects and take a long time to run. Our test scripts should always isolate unit tests from e2e tests. That isolation is not currently preserved.

Expected behavior:

• npm test only invokes unit tests (and runs lint)
• npm test:e2e only invokes e2e tests

[ericelliott]

Oops, this was fine, actually. npm run test:unit isolates unit tests, npm run test:e2e isolates e2e - npm run test runs all of them, AND lint. quick sanity check shortcut.