Generates a JSON file that contains information about the addons config.
The JSON file is sent by Widgetbook CLI to Widgetbook Cloud when a build
is pushed.
Builder for the UseCase annotation.
Creates a .usecase.widgetbook.json file for each .dart file containing
the UseCase annotation. The file contains a list of UseCaseMetadata
json objects representing the annotated elements. These files are used
later on by other builders to generate more code.