[Data catalog] Move CTAs into dbt DAG

[jeancochrane]

Currently, the dbt DAG only manages our views (as materialized: view models) and defines the rest of our data as source models that are managed outside the DAG. For many of our data sources this will continue to be appropriate, but we would like to move the CTA queries as defined in aws-athena/ctas/ into the DAG as materialized: table models.

Implement this change so that we can manage our CTAs with dbt. Continue to follow the pattern established in #41 by symlinking from the dbt/models/ directory to the aws-athena/ctas/ directory so that we can maintain git history for these models.