List OpenVINO available devices

[ravi9]

Provide a mechanism (e.g., llama-bench --list_devices) to list all available execution devices supported by OpenVINO.

[haarika-madaka]

@ravi9
I am working on this issue. Kindly assign to me.
There are two possible outputs that we can get with only changes done to backend code. let me know which one is preferred so I can go ahead and submit a PR to the dev branch.

llama-bench --list-devices
Available devices:
CPU: OpenVINO (31623 MiB, 31623 MiB free)
GPU: OpenVINO (31623 MiB, 31623 MiB free)
NPU: OpenVINO (31623 MiB, 31623 MiB free)

or

llama-bench --list-devices
Available devices:
CPU: CPU (31623 MiB, 31623 MiB free)
GPU: GPU (31623 MiB, 31623 MiB free)
NPU: NPU (31623 MiB, 31623 MiB free)

[haarika-madaka]

Attaching the PRD and reference documents that I received for this topic.

Some additional changes not listed in PRD and files below are:

To print the current selection of the device.
To use core.available_devices() for correct output.

linux_dGPU_device_Properties.txt
linux_lnl_device_Properties.txt
PRD_ ggml_ov_Device_Enumeration.md
windows_device_Properties.txt

[haarika-madaka]

https://github.com/ravi9/llama.cpp/pull/256