Developers should be able to define custom scope colors

[kolyaventuri]

Right now, all scopes are green. While nice, being able to see which scope has been logged at a glance would be useful.

This will require expanding our color table (do we want to replicate something like chalk to handle 256-color terminals?)

[kolyaventuri]

type ScopeObjectType = {|
  name: string,
  color?: Color
|};

type ScopeType = string | ScopeObjectType;