Add amdsmi backend

AMD seems to move away from ROCM SMI to AMD SMI. This library is used for the new AMDSMI PMT backend. The new backend is tested with ROCm 6.2.0 on a AMD W7700 and on AMD MI210.

A few notes:

• The amdsmi_processor_handle struct has (amongst others) fields current_socket_power and average_socket_power. Only the average_socket_power seems to be set by the amdsmi_get_power_info call. We may want to revisit this later, maybe this will change in later ROCm releases or on different GPUs.
• The code has the same structure as the NVML backend, with separate AMDSMI and AMDSMIImpl class, the ROCM class should be refactored similarly (outside the scope of this MR)
• Also, we may want to rename the ROCM backend to RSMI (outside the scope of this MR)
• No CMake helper file is used (e.g. Findamd_smi.cmake), simply setting CMAKE_PREFIX_PATH=/opt/rocm also works fine and is arguably nicer + more future-proof.