Migrate CRA scripts to more configurable build system

[ayyrickay]

Not totally sure about this one yet, but Parcel may be a much simpler build tool - and that may be nice for us, since this tool doesn't really need to scale.

Additionally, it appears that parcel is fairly easy to replace with Webpack should we need more advanced configuration down the line. But for now, this could simplify a lot of our woes with react-scripts and our migration to typescript and npm workspaces

UPDATE: Parcel brings it own issues, NextJS, Webpack are alternatives

Our core issues include things like: Being blocked on #77, because the targeting for typescript and JS isn't being handled totally properly in the react-scripts config. Or being blocked on #79, because the frontend and backend are using different versions of eslint.

Webpack is maybe too much config for our needs, in some ways, but the flexibility it offers seems necessary for some of the things we're trying to do.