[FIX][TIRx][CUDA] Support low-precision, tensor-map and cluster kernels in CUDA-host bundles

[spectrometerHBH]

A CUDA-host bundle (tvm.backend.cuda.export_cuda_host, #20395) compiles device and host code as one NVCC C++ translation unit. Building the native kernels of mlc-ai/TIRx-kernels this way exposed several patterns that the bundle could not compile or launch:

• Low-precision types in the host pass. The CUDA device header included cuda_fp16.h, cuda_bf16.h, cuda_fp8.h, cuda_fp6.h and cuda_fp4.h (and defined the fp8_e4_t-style aliases) only under defined(__CUDA_ARCH__). NVCC's host pass then fails on kernel signatures that use half or nv_bfloat16. The guards now also admit the host pass (!defined(__CUDA_ARCH__) || __CUDA_ARCH__ >= N); NVRTC and device-only NVCC compilation always define __CUDA_ARCH__ and are unchanged.
• Tensor-map parameters. The host wrapper bound a T.TensorMap() parameter as CUtensorMap* x = ((void*)...), which C accepts and C++ rejects. It now casts explicitly.
• Argument types at the launch. Host C code spells some device types differently (bfloat16 is uint16_t* on the host, nv_bfloat16* in the kernel), so the direct <<<>>> launch did not type-check. Launches now go through a small helper that converts each argument to the kernel's own parameter type and calls cudaLaunchKernelEx.
• Launch attributes. clusterCtaIdx.*, preferredClusterCtaIdx.*, programmatic dependent launch and cooperative launch were rejected. They now become the corresponding cudaLaunchAttributes, following CUDAWrappedFunc in the CUDA runtime module (including cudaFuncAttributeNonPortableClusterSizeAllowed for cluster launches and omitting a unit preferred cluster). Required block dimensions remain unsupported and are still diagnosed.

Testing

On B200 (sm_100a), CUDA 13.2, this branch:

• tests/python/codegen/test_target_codegen_cuda.py -k cuda_host: 8 passed (4 tests, each under NVCC and NVRTC device compilation). New tests:
  • bfloat16 buffers with a two-CTA cluster launch: runs and checks both the values and each CTA's cluster rank ([0, 1, 0, 1]);
  • a programmatic dependent launch flag: runs and checks the launch attribute;
  • a tensor-map parameter: compiles the bundle with NVCC.
• tests/python/codegen/test_target_codegen_cuda.py, tests/python/tirx/codegen/test_codegen_cuda.py, tests/python/tirx-transform/test_tir_transform_split_host_device.py, tests/python/tirx-transform/test_tir_transform_lower_tvm_builtin.py: 487 passed, 8 skipped. The remaining 120 failures are all parametrizations of test_ptx_cp_async, which fails while parsing its TVMScript body (prim._OpEQ receives a string), before any code generation; this change does not touch that path.

The same change is proposed for the v0.27.0 release branch in #20489. There it was also verified end to end with mlc-ai/TIRx-kernels (whose kernels currently target the v0.27.0 script APIs): with mlc-ai/TIRx-kernels#3, all 220 correctness configs of its nine single-GPU native kernels pass when every CUDA compile is built with host="cuda_host", bundled with export_cuda_host, compiled by tvm_ffi.cpp.build_inline and loaded with tvm_ffi.load_module.