Determine happier path for using graphs in test fixtures

[johnatawnclementawn]

For some of the CLI tools, we use test fixtures found here. In hindsight, using the fixtures in this way doesn't seem sustainable. We recently ran into an issue where new constraints were added to the node model, and because these models were created when that constraint was not implemented, the fixtures failed to load and tests failed. The example graphs should be migrated with new db migrations, but the migrations fire before fixtures are loaded.