refactor: move DataProvider to app level with deferred loading

[mchen11077]

Fixes #481

Summary: Move DataProvider to App and keep it lazily loaded.

Changes

• Mount PageParamsProvider and DataProvider in App
• Load providers via dynamic import in useEffect
• Remove providers from DataPage

Test Plan

• npm run dev
• Check /intro renders immediately
• Check /data loads correctly
• npm run build and confirm DataProvider is a separate chunk

Checklist

• Data available globally
• No blocking on initial render
• DataProvider not in main bundle

[conradarcturus]

1 minor change.

This is partially deferred -- but the way you set it up, you are blocking the whole page render until the 2 components have been loaded. If you have cached the page it is pretty fast, but we should return the children without providers. However we expect people to load the page with mobile devices and/or limited internet connections.

You can test out the page with limited network connections in the chrome debug tools, click the icon with the laptop/cellphone to open with mobile device specs and throttle the network connection to mid-tier or low-tier mobile.

[conradarcturus]

It looks like something may have been merged incorrectly.

Apologies if you were waiting for me for awhile for comments. Since there are so many changes I usually only check in when it says "waiting for review" (it still says "changed requested" right now, you can click a button to switch it back to "waiting for review"). Also if there are build or test errors I usually ignore it too, expecting you to fix it before I get back to the change.