Add various test fixtures for project configurations

[agjohnson]

We don't have a standardized set of projects that we should be testing against locally/in QA, but could have some shared/automated way to establish projects with various configurations:

• Subprojects
• Translations
• Superproject/landing page with subprojects
• Single version project
• ... TBD

This would help with testing search, hosting, proxito, etc.

I would also say it would be great to have these same project fixtures set up in community/commercial for QA testing. We already have some of this configuration in both stacks at least, but I feel we might all have our own way of testing these sorts of configurations.

[humitos]

We have a PR open that does a refactor of the fixtures. We can include these changes into that refactor as well: #9411