[KHR] Provide an alternative to <sycl/sycl.hpp>

[gmlueck]

Cherry pick #814 from main
(cherry picked from commit 0e2ded4)

[gmlueck]

The "sycl_khr_split_headers" KHR was ratified, and the working group decided in the meeting on October 1, 2026 to publish it. This PR cherry picks the KHR to the "sycl_2020" branch. That KHR will therefore be published whenever the WG decides to publish the next maintenance revision.

[KornevNikita]

@gmlueck I'm curious - do you update the "Acknowledgements" chapter before the new revision publication yourself, or it should be done by the developers?

[gmlueck]

@gmlueck I'm curious - do you update the "Acknowledgements" chapter before the new revision publication yourself, or it should be done by the developers?

I usually do it myself before publishing a new revision, but it's OK for developers to add themselves. In fact, that saves me some time later. I think you are already in the Acknowledgements section, but we should add @koparasy, who was an author on this KHR. @koparasy feel free to create a PR (against the "main" branch") adding yourself to that section. Note the sorting -- first by organization then by last name.

[KornevNikita]

Thanks for the clarification. I can create a PR since I started this discussion. I believe we should also add @AlexeySachkov since he kicked this off. Although I'm not sure about the organization?

[AlexeySachkov]

Thanks for the clarification. I can create a PR since I started this discussion. I believe we should also add @AlexeySachkov since he kicked this off. Although I'm not sure about the organization?

I think that you should write Intel, since all my work I did on the extension was whilst I was employed there.

[gmlueck]

Oh yes. We should add @AlexeySachkov also. I thought he was already in the Acknowledgements chapter, but I see that he is not.

[KornevNikita]

#1065