rattler-build, python version_independent, cuda 12/13 variants

[casperdcl]

• move from conda build to rattler-build
• use conda-forge instead of CPM for cccl
• cuda_version_major=None,12,13 variants
  • maybe just cuda_version_major=None,12 if cuda-cudart-dev=12.* static linking is forward-compatible with platform __cuda=13.*
• CI: rattler with sccache for faster builds
• fix windows failures (replaces/closes win py313 #222, fixes CI: CUDA, conda, windows #195)
  • inexplicable hateful fix: run https://github.com/ilammy/msvc-dev-cmd for win-cpu but not for win-cuda
  • can't see anything relevant in https://rattler-build.prefix.dev/dev/windows_quirks/
• python version-independent
  • https://docs.conda.io/projects/conda-build/en/stable/resources/define-metadata.html#python-version-independent-packages
  • https://conda-forge.org/docs/maintainer/knowledge_base/#non-version-specific-python-packages
  • seems not to work as per Add an option to create arch specific, python version independent pkgs conda/conda-build#5456 (comment) (the conda-test jobs all forcefully install python3.10)
  • requires conda-build>=25.3
  • requires rattler-build https://rattler-build.prefix.dev/latest/build_options/#python-package-version-independence

[casperdcl]

Inexplicable hateful fix: run https://github.com/ilammy/msvc-dev-cmd for win-cpu but not for win-cuda. makes no sense.

Can't see anything relevant in https://rattler-build.prefix.dev/dev/windows_quirks/.