feat: add dev app

[teallarson]

Adds a NextJS dev app to ease local development:

• developing the widget
• developing the Airbyte webapp within the widget

[girarda]

@teallarson what's the benefit of a separate app instead of adding an env var to the existing one controlling whether we pull the embedded library from the cdn or locally?

[teallarson]

• dev app also adds being able to modify the webapp url (not relevant for an external demo)
• if/when we split out the demo into a separate repo, we don't have to worry about checking out two separate repos to run this locally
• the demo app does not support hot module reloading unless we add a web server, which was something we removed from the demo app last week. it's a truly annoying dev experience.

[girarda]

lgtm 🎸

[girarda]

can you add an example or write down that when running locally, this needs to include the /api/public? It might be implied from the variable name, but I suspect I know because I got burnt before and it's not that obvious

[joeykmh]

maybe name it NEXT_PUBLIC_AIRBYTE_PUBLIC_API_BASE_URL? Verbose, but that would have saved me a couple times 😄

[joeykmh]

unnecessary try/catch here?

[joeykmh]