[IDAG] Add new threading facilities

[fknorr]

This PR upstreams and tests two threading facilities required for IDAG execution: The in-order thread_queue and the double_buffered_queue for fast communication between threads.

• async_event gains the ability to return results from async operations (in practice always pointers = results from sycl::malloc, which is why I opted to make the result typpe void* instead of std::any)
• thread_queue takes functors as submissions and returns async_events while providing timing/profiling capabilities for host task, host copy and allocation operations. This will replace the CTPL thread pool, which would require a lot of boilerplate to keep in while providing little benefit, because with OoO dispatch, we don't have a need for pools with > 1 thread anymore.
• double_buffered_queue generalizes the queueing mechanism that's currently in place between main- and scheduler thread and ensures the consumer is contended as little as possible. This is a stand-alone component now because it will also be used between scheduler and executor threads.

I do realize there's a staggering number of things called queue now.

[github-actions[bot]]

Check-perf-impact results: (7b849de16ff11660b98988ab0b032db7)

:question: No new benchmark data submitted. :question:
Please re-run the microbenchmarks and include the results if your commit could potentially affect performance.

[coveralls]

Pull Request Test Coverage Report for Build 9665184999

Details

• 84 of 93 (90.32%) changed or added relevant lines in 5 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.07%) to 94.609%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
include/async_event.h	7	11	63.64%
include/thread_queue.h	52	57	91.23%
<!--	Total:	84	93	90.32%	-->

Files with Coverage Reduction	New Missed Lines	%
include/utils.h	2	89.74%
<!--	Total:	2		-->

Totals
Change from base Build 9661291153:	-0.07%
Covered Lines:	7132
Relevant Lines:	7357

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9725185072

Details

• 84 of 92 (91.3%) changed or added relevant lines in 5 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 94.627%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
include/async_event.h	7	10	70.0%
include/thread_queue.h	52	57	91.23%
<!--	Total:	84	92	91.3%	-->

Files with Coverage Reduction	New Missed Lines	%
include/utils.h	2	89.74%
<!--	Total:	2		-->

Totals
Change from base Build 9661291153:	-0.05%
Covered Lines:	7132
Relevant Lines:	7356

---

💛 - Coveralls

[fknorr]

Why does OoO dispatch alleviate the need for a thread pool?

Because OoO assignment addresses individual threads as lanes, whereas before, the thread pool decided which job would get assigned to which pool thread. The backend will simply maintain an array of thread_queues and explicitly index into it with the lane id.