moving to src layout

src/csrc/fft.cu

src/csrc/grid_descriptor_mgr.cc

src/csrc/halo.cu

src/csrc/include/checks.h

src/csrc/include/fft.h

src/csrc/include/grid_descriptor_mgr.h

src/csrc/include/halo.h

src/csrc/include/helpers.h

src/csrc/include/jaxdecomp.h

src/csrc/include/logger.hpp

src/csrc/include/perfostep.hpp

src/csrc/include/transpose.h

src/csrc/jaxdecomp.cc

src/csrc/transpose.cu

src/jaxdecomp/__init__.py

src/jaxdecomp/_src/__init__.py

src/jaxdecomp/_src/cudecomp/__init__.py

src/jaxdecomp/_src/cudecomp/fft.py

src/jaxdecomp/_src/cudecomp/halo.py

src/jaxdecomp/_src/cudecomp/transpose.py