Move chronik functions to their own dir and out of utils

Unit tests and mocks should still be refactored for maintainability. But that should happen after the move.

This diff

• Moves all mocks used by chronik unit tests into src/chronik/fixtures/mocks.js
• Copies src/utils/chronik.js to src/chronik/index.js
• Copies chronik unit test file to new dir and updates imports for new mock location
• Deletes old mock files
• Updates imports

It's a lot, but npm test confirms no changes

npm test