[SYCL][Doc] Add sycl_ext_oneapi_device_is_integrated spec extension

[dm-vodopyanov]

No description provided.

[aelovikov-intel]

Please update description on how it's different from https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html#api:info-device-host-unified-memory

[gmlueck]

I saw that an earlier version of this PR added the query to sycl_ext_intel_device_info. Why did you change your mind and add it as a separate extension?

If we need to add this query as both an info descriptor and also an aspect (telling whether the info descriptor is supported), then it might be better to add it to sycl_ext_intel_device_info because it matches the pattern we use there.

[gmlueck]

I'd suggest a slight rewording here because the difference between "integrated" and "discrete" isn't always clear cut:

This extension allows host code to check whether a SYCL GPU device is "integrated" or "discrete". An integrated GPU device often shares memory with the host CPU, while a discrete GPU is often a separate card with its own memory. However, some GPU devices may not fit neatly into either category, so implementors may provide their own judgement when categorizing a GPU device as "integrated" vs. "discrete".

@bashbaug does this seem like a reasonable description? Any suggestions?

[gmlueck]

LGTM!

[github-actions]

@intel/llvm-gatekeepers please consider merging