Introduce process file descriptor (pidfd) based process monitoring for Linux #163

Job	Run time
CMake Build	58s
Test / macOS (Xcode 16.3 - sequoia - ARM64)	1m 2s
Test / Windows (nightly-main - windows-2022)	10m 31s
Test / Windows (6.1 - windows-2022)	7m 41s
Test / Linux (6.1 - noble)	6h 0m 3s
Test / Linux (6.1 - focal)	6h 0m 2s
Test / Linux (6.1 - rhel-ubi9)	6h 0m 3s
Test / Linux (nightly-main - rhel-ubi9)	6h 0m 2s
Test / Linux (nightly-main - noble)	6h 0m 3s
Test / Linux (6.1 - jammy)	6h 0m 4s
Test / Linux (nightly-main - focal)	6h 0m 2s
Test / Linux (nightly-main - jammy)	6h 0m 2s
Soundness / YAML lint check	5s
Soundness / License headers check	5s
Soundness / Shell check	41s
Soundness / API breakage check	0s
Soundness / Python lint check	7s
Soundness / Broken symlinks check	3s
Soundness / Format check	0s
Soundness / Unacceptable language check	0s
Soundness / Documentation check	0s
	2d 0h 21m 34s

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