CircleCI: Add a test to run prettier

[Asartea]

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1. Description of the Feature Request: We've added prettier, but aren't currently checking if an file actually complies with it. Specifically, I think it would make sense to split the current test-and-linters into a new tests (which runs jest) and a linters (which runs eslint and prettier)

2. Acceptance Criteria:

• [ ] CircleCI runs prettier

3. Additional Information: