Upgrade core dependencies

[didoesdigital]

After breaking up App.js, there are some major upgrades to tackle:

• react router 5 to 6 ✅ and 7
• react 17 to 18 and 19

We may also need to replace react-loadable and switch from create-react-app. That could mean using react router "as framework" (aka Remix), react router "as library", or vite. That will influence how we manage code splitting without react-loadable. Switched to Vite, using built in React lazy/Suspense.

Typescript ✅ and storybook are also major versions behind.

I think step 1 after breaking up App.js will be upgrading react router to v6. ✅

A lot dependencies are getting difficult to manage because of create react app being deprecated and stuck on old versions, so migrating that may need to come sooner than later. ✅