The local development workflow should "just work" for most projects

[erquhart]

Is your feature request related to a problem? Please describe.

The local development flow is what most devs expect when running the CMS locally, but it isn't enabled by default, and often requires manually starting a server. It's also not obvious in the UI when the local development is enabled.

Describe the solution you'd like

Local development should "just work" for popular workflows, and it should be obvious in the UI.

Issues should be created for each of the following:

• Indicate local development mode in UI #3286: Make development mode obvious in UI
• Integrate dev server with gatsby-plugin-netlify-cms
• Integrate dev server with victor-hugo

Describe alternatives you've considered

Additional context