Code organization and test refinements

[Starttoaster]

This PR:

• Reorganizes all of the controller logic code into different packages to make the API/controllers easier to build and maintain. Changed files in internal/controller/**.
• Adds contribution rules surrounding API struct fields. Changed CONTRIBUTING.md.
• Changes the API to follow these contributing guidelines; controller logic updated to adopt the new API without actual usage changes. Changed files in api/ and internal/controller.
• Adds substantial testing to controller logic and API struct unmarshaling from yaml. Changes files like api/v1/*_test.go and internal/controller/*_test.go.
• Adds a config toggle to disable (defaults to enable) a chia-exporter sidecar container for all chia deployments/statefulsets. No functionality change, this was previously hardcoded to enabled, it just adds a provision to turn it off.
• Adds documentation for each of the custom resources in this operator. Adds files in docs/
• Fixes bug with mounting persistent volumes in multiple services.