Previously, we were using 8.0.0rc1.
In particular, this upgrade means we need to explicitly
import more rules, as they've been moved out of the core bazel repo.
While I would have preferred to add a proper unit test, this required
more infrastructure for mocking system calls. Instead I made `qltest.sh`
accept a `//codeql-extractor-env` header and used that to write a QL
test exercising the `RUN_UNDER` functionality.
