Add boilerplate for local UI

[lewish]

For a number of future features, we plan to serve a UI on localhost that can aid with a number of tasks such as:

• Viewing the compiled output of a project (and recompiling automatically when it changes)
• Running new deployments
• Viewing the results of a run
• Setting up a warehouse connection

To do all of this, we should add a new command, dataform serve that starts up a local web server, and serves a basic react app that we can add these features to.

[lewish]

I'm going to close this for now as it's not on the roadmap.