Windows compatibility fixes to FindHIP.cmake.

[ScottTodd]

See https://github.com/ROCm/TheRock/issues/526 and https://github.com/ROCm/TheRock/pull/583. Together, these changes help get the CMake configure + build steps for PyTorch on Windows further along.

Fix find_path search in the case where hipconfig with no suffix is not present

When using find_path, CMake searches for "a directory containing the named file". On Windows, hipconfig has three extensions: .bat, .exe, and .pl. None of these match the unsuffixed search pattern, so this adds a ${CMAKE_EXECUTABLE_SUFFIX} there.

Remove .bat suffix appending in favor of using the .exe discovered by find_program

The find_program(HIP_HIPCC_EXECUTABLE NAMES hipcc ...) and find_program(HIP_HIPCONFIG_EXECUTABLE NAMES hipconfig ...) commands should both find programs with the .exe suffix. Per the docs, they will not find programs with .bat or .sh suffixes unless those suffixes are explicitly requested: https://cmake.org/cmake/help/latest/command/find_program.html.

To search for scripts, specify an extension explicitly:

if(WIN32)
  set(_script_suffix .bat)
else()
  set(_script_suffix .sh)
endif()

find_program(MY_SCRIPT NAMES my_script${_script_suffix})

The code from https://github.com/ROCm/hip/commit/73b520a2e0eebdfce08ba495fc017f346fa673a0 and https://github.com/ROCm/hip/commit/952028a888a63f377a1763337480defd4de12d92 appended a .bat suffix onto discovered file names where I believe the original names should just be used instead. I might be missing some edge case where .bat is needed, but I don't see any other context on those commits.