Add schema for configurations

[jopetty]

Use the @dataclass annotation to create a defined schema for all the YAML configs we use. This will make it easier to type-check configs and provide clear documentation on what needs to be included in each.

See the Hydra example for more information.

[jopetty]

I don't think this makes sense for the 1.0 release. The nature of the configurations is so in flux right now that adding structured configs for most things seems like it won't bring much benefit yet.