Introduce process file descriptor (pidfd) based process monitoring for Linux #154

Job	Run time
CMake Build	58s
Test / Windows (6.1 - windows-2022)	8m 3s
Test / macOS (Xcode 16.3 - sequoia - ARM64)	2m 53s
Test / Windows (nightly-main - windows-2022)	11m 0s
Test / Linux (nightly-main - noble)	3h 14m 30s
Test / Linux (6.1 - noble)	3h 14m 30s
Test / Linux (6.1 - rhel-ubi9)	3h 14m 27s
Test / Linux (6.1 - jammy)	3h 14m 27s
Test / Linux (6.1 - focal)	3h 14m 29s
Test / Linux (nightly-main - jammy)	3h 14m 29s
Test / Linux (nightly-main - rhel-ubi9)	3h 14m 28s
Test / Linux (nightly-main - focal)	3h 14m 27s
Soundness / License headers check	5s
Soundness / API breakage check	0s
Soundness / Shell check	40s
Soundness / Documentation check	0s
Soundness / YAML lint check	4s
Soundness / Python lint check	10s
Soundness / Broken symlinks check	6s
Soundness / Unacceptable language check	0s
Soundness / Format check	0s
	1d 2h 19m 46s

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