[ROCm] Rework ROCm build to use ROCm version instead of HIP version - #1888

Summary

Use the ROCm release version consistently when naming and selecting bitsandbytes native libraries. HIP and ROCm versions can diverge, so relying on hipconfig or torch.version.hip alone can select a missing or incompatible binary.

Changes

Build and packaging

• Keep the existing HIP build backend (COMPUTE_BACKEND=hip and BUILD_HIP).
• Detect the ROCm release from ${ROCM_PATH}/.info/version, ${ROCM_PATH}/core/.info/version, or rocm-sdk version.
• Fail with guidance when the ROCm version cannot be detected; -DROCM_VERSION=<version> remains an optional override and accepts dotted or compact forms.
• Require ROCM_PATH for Windows wheel-based SDK builds; Linux warns before defaulting to /opt/rocm.
• Pass the CI matrix ROCm version explicitly to CMake and verify that the expected versioned artifact was produced.
• Require hipBLASLt for ROCm builds and remove the obsolete NO_HIPBLASLT path.

Runtime library selection

• Prefer torch.version.rocm; warn and fall back to torch.version.hip when the ROCm field is unavailable.
• Accept dotted or compact values for both BNB_ROCM_VERSION and BNB_CUDA_VERSION.
• Warn when an override for the opposite backend is set.
• Match packaged library filenames strictly and support compact tags with double-digit major versions.
• Select binaries in this order:
  1. exact version;
  2. newest older binary from the same major;
  3. oldest newer binary from the same major;
  4. for ROCm only, apply the same older-first policy across majors with a stronger compatibility warning.
• Keep CUDA fallback restricted to the same major version.

Diagnostics and documentation

• Report torch.version.rocm and torch.version.hip separately.
• Document build-time detection, runtime overrides, and compatibility fallback behavior.
• Add focused CUDA/ROCm tests for exact selection, same- and cross-major fallback, dotted/compact overrides, invalid overrides, and wrong-backend overrides.

Validation

• pytest -q tests/test_cuda_setup_evaluator.py — 19 passed
• Ruff and formatting checks pass for modified Python files
• bash -n .github/scripts/build-rocm.sh
• ROCm CMake configure succeeds using the wheel-installed SDK and .info/version
• Local ROCm native build and bitsandbytes GPU sanity check succeed

Compatibility

There is no backend rename in this PR: downstream builds using -DCOMPUTE_BACKEND=hip continue to work. ROCm cross-major fallback is best-effort and emits a warning because compatibility and packaged GPU targets are not guaranteed.