This make the predicate give back sensible results on (upgraded) databases
where we do not have expanded arguments, and avoid having to write case
distinctions in places where we would want to use `getExpandedArgument`.
This PR separates the core cpp packs into `codeql/cpp-queries` and
`codeql/cpp-all`.
There are very few lines of code changed. Almost all changes are moving
files around.
