CLI Build Widget

[kitsonk]

Enhancement

With the changes that will be delivered with cli-build-app (see #197) there is an area of functionality that is not covered by the build of an "app". This is the functionality to create a redistributable of a widget or a set of widgets for consumption in other libraries.

This epic is designed to track the tasks related to this feature. At a minimum, the use cases that need to be addressed are:

• The ability to "build" a widget or set of widgets, so that it can be easily integrated and imported into other applications, including the appropriate TypeScript typings.
• The ability to "build" a widget or set of widgets that can be used as custom elements/Web Components without further build processing by a consumer.

[agubler]

This has been covered by the cli-build-widget command - currently supports a target of a custom element with a future enhancement to build individual native dojo 2 widgets.