Remove Babel config and dependencies

[sawyerh]

Context for reviewers

• A code comment indicated the Babel config was needed for our tests to work, which may have been accurate at a certain point, but no longer is now that our Jest setup utilizes the next/jest package. More context here.
• It appears that the Babel config was also allowing us to write the Storybook config in TypeScript, but we can still support type checking of that file without Babel (see file changes).
• Now that the Babel config isn't present, Next.js and Jest will utilize SWC instead of Babel, which is supposed to result in improved performance.

Testing

Type checking still works in the Storybook JS config file: