Billing budget factory

[ludoo]

This implements support for a billing budgets factory in the billing account module. A subsequent PR will refactor factories across modules

• align all factory variables to the same format used here
• move the project factory to the project module (for projects)
• move the service account factory to the service account module and add support for the full interface
• update the FAST project factory to leverage project, service account, and billing budget factories
• remove the project factory from blueprints and replace the blueprint project factory subfolders with a README file listing all modules that support a factory