Add CUDA support to HerculesBox

• Call CUDA runtime functions in HerculesBox to move collections on / off the GPU.
• Call correct __ptr function in generated Rust code.

.gitlab-ci.yml

-build-job:
-  stage: build
-  script:
-    - cargo build
-
 test-job:
   stage: test
   script:
     - cargo test
+    - cargo test --features=cuda