There isn’t support for it currently in liquibase. Liquibase knows nothing about packages or package bodies, it just happily executes whatever SQL you give it.
There is support for packages in Datical, but not the functionality you are looking for.
My only concern is relying on a metadata query to determine the sql to run. It works fine when running an update, but updateSql will not work because you don’t know what the state of the package would have been. That being said, sometimes that tradeoff is worth it for the functionality you are looking for.
The liquibase-oracle extension would definitely be the place to put the support since it is pretty Oracle specific. I always appreciate pull requests, so feel free to see what you can do and let me know if you have any questions.