Add support for multi-arch and multi-platform cuda toolchains

[charleysaintNV]

This MR adds support for multiple architectures and multiple versions of a toolchain. Using the redis_json you can create multiple versions of a toolchain:

cuda.redist_json(
    name = "cuda_13_0_2",
    version = "13.0.2",
    platforms = [
        "linux-x86_64",
        "linux-sbsa",
    ],
)
cuda.redist_json(
    name = "cuda_13_0_0",
    version = "13.0.0",
    platforms = [
        "linux-x86_64",
        "linux-sbsa",
    ],
)
cuda.redist_json(
    name = "cuda_12_8_0",
    version = "12.8.0",
    platforms = [
        "linux-x86_64",
        "linux-sbsa",
    ],
)

cuda.toolkit(name = "cuda")
use_repo(cuda,"cuda")

then using a set of flags in .bazelrc you can control which version of the toolchain to use in a given config:

build --@rules_cuda//cuda:exec_platform="linux-x86_64"
build --@rules_cuda//cuda:target_platform="linux-x86_64"
build --@rules_cuda//cuda:version="13.0.0"

[steple]

Thanks for adding this, I think this will be very useful.

[charleysaintNV]

pushed a new commit with the versions stuff moved around and all in one place at least and I changed the name of the nvcc_platform and runtime_platform to exec and target