first working HIP test case

src/pystencilssfg/composer/gpu_composer.py

src/pystencilssfg/ir/__init__.py

src/pystencilssfg/ir/call_tree.py

tests/generator_scripts/index.yaml

tests/generator_scripts/source/HipKernels.harness.cpp

tests/generator_scripts/source/HipKernels.py