Pubsub topics can now have
schemas (https://cloud.google.com/pubsub/docs/admin#schemas). This PR adds an
option to set the schema settings and create a new optional resource of type
`google_pubsub_schema` attached to the `google_pubsub_topic`.
- Ensure all variables and outputs are sorted
- Ensure all variables and outputs have a description
- Add data-solutions/data-platform-foundations to linter
Fix all modules to follow these new conventions.