Sandbox proxy / dual dev server loader

[ryanblock]

We need to run sandbox alongside other frontend frameworks' dev servers (e.g. Vue, Gatsby, etc.).

While this shouldn't be a core responsibility of sandbox itself, we should have some kind of solution to enable sandbox to work in tandem and not clobber another dev server (and vice versa).

How should we go about this?

We've internally discussed some kind of dual-tab or dual-pane system, but very open to ideas!