Provide hooks to allow extensions that can integrate with other tooling.

[big-andy-coates]

Provide hooks in the resource initialisation routines to allow integration with other tooling. These should support both the resource initialisation done when initialising Creek in a microservice, and in the init tool, e.g. think Topic creation, Schema creation, s3 bucket creation, etc.

The hooks should be sufficient to provide a pluggable extention model to allow tooling to do "something" with the component metadata. For example, publish information about data products (topic or bucket + schema + ownership etc) to a data catalog.