Add old tests

src/pystencils_autodiff/__init__.py

src/pystencils_autodiff/_layout_fixer.py

src/pystencils_autodiff/adjoint_field.py

src/pystencils_autodiff/autodiff.py

src/pystencils_autodiff/backends/_torch_native.py

src/pystencils_autodiff/lbm/adjoint_boundaryconditions.py

tests/backends/lltm_cuda.cpp

tests/backends/lltm_cuda_kernel.cu

tests/backends/test_torch_native_compilation.py

tests/lbm/_assignment_transforms.py

tests/lbm/_layout_fixer.py

tests/lbm/_utils.py

tests/lbm/adjoint_field.py

tests/lbm/autodiff.py

tests/lbm/backends/_pytorch.py

tests/lbm/backends/_tensorflow.py

tests/lbm/backends/_tensorflow_cpp.py

tests/lbm/backends/_torch_native.py

tests/lbm/backends/torch_native_cpu.tmpl.cpp

tests/lbm/backends/torch_native_cuda.tmpl.cpp