* Implement dump_golden_schema command in devtool
Add a dump_golden_schema command so that we can generate the golden schema
in-place without having to do the test -> fail -> copy -> test dance.
Refactor the SQL container functionality from GenerateSqlCommand. There is
some duplication of code between the dump command and SchemaTest which should
be dealt with in a subsequent PR.
* Reformatted and changes in response to review
* Fix getDockerTag() usage
* Fix "leaked resource"