[Spec change] [KHR] add sycl_khr_queue_size_queries

[sycl-issue-bot]

Please review whether KhronosGroup/SYCL-Docs#700 by @TApplencourt requires any changes to the CTS.

If changes are required: Open a new PR addressing the changes and link it to this issue.
If no changes are required: Close this issue and proceed with the spec PR.

[TApplencourt]

Preliminary work done on: https://github.com/KhronosGroup/SYCL-CTS/tree/khr_queue_empty_query
Wait that we settle on name of function before making the PR

[gmlueck]

@TApplencourt will you create a PR for the CTS test?

[gmlueck]

Oh, never mind. I see that you did this already in #1031. Can this issue be closed now?

[TApplencourt]

Indeed!