Refactor: support modern cuSOLVERMp with NCCL

[dzzz2001]

Summary

• Add NCCL backend support for cuSOLVERMp initialization (version >= 0.70)
• Retain libcal backend compatibility for older cuSOLVERMp versions (< 0.70)
• CMake automatically selects the appropriate backend based on cuSOLVERMp version
• Update toolchain documentation

Closes #6940

Background

Starting from cuSOLVERMp v0.7.0, NVIDIA has transitioned from the Communication Abstraction Library (CAL) to using NCCL directly. This PR adds NCCL support while maintaining backward compatibility with older versions using CAL.

Build Instructions

To compile ABACUS with cuSOLVERMp support:

cmake -DENABLE_CUSOLVERMP=ON -DNVHPC_ROOT_DIR=/opt/nvidia/hpc_sdk/Linux_x86_64/xx.x/ ...

Note: If you have loaded the NVHPC module file, NVHPC_ROOT_DIR will be automatically inferred and does not need to be set manually.

[dzzz2001]

I updated some toolchain-related docs. @QuantumMisaka , could you please review them? The toolchain might need further changes

[ZhouXY-PKU]

#6758 can also be closed.