Extend platform API with functions for setting thread scheduling policy, core affinity and priority + remove C11 as platform #2658

Job	Run time
check-labels / check	8s
build-trace-tools / run (ubuntu-latest)	3s
unit-tests-multi / run (ubuntu-latest)	6s
build-trace-tools / run (macos-latest)	8s
unit-tests-multi / run (macos-latest)	18s
build-rti / run (ubuntu-latest)	7s
build-trace-tools / run (windows-latest)	28s
unit-tests-multi / run (windows-latest)	1m 6s
build-rti / run (macos-latest)	22s
build-rti / run (windows-latest)	14s
fetch-lf / extract-ref	4s
unit-tests-single / run (ubuntu-latest)	16s
unit-tests-single / run (macos-latest)	6h 0m 14s
unit-tests-single / run (windows-latest)	58s
lf-default-zephyr	0s
lf-default-arduino	0s
lf-python	0s
lf-gedf-np	0s
lf-adaptive	0s
lf-default / regular-tests (ubuntu-latest)	25m 37s
	6h 30m 9s

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