fix CUDA/HIP cmake flags
fix CUDA/HIP cmake flags

- CUDA
  - do not set `-G` for nvcc when CMake build type is debug
    - `-G` will not only add debug symbols it also set `-O0`
  - ALPAKA_HIP_KEEP_FILES
    - remove the default folder `nvcc_tmp` -> this is not working with
multiple targets e.g. alpaka examples
  - remove that `ALPAKA_HIP_KEEP_FILES` is activated when
`ALPAKA_CUDA_SHOW_CODELINES` is used
- HIP
  - fix the keep files flag
  - fix how debug symbold will be added
  - do not set `-G` for HIP-nvcc when CMake build type debug is used

BenjaminW3/alpaka,BenjaminW3/alpaka