Collect number of process FDs and /proc/self/limits #268

Job	Run time
Lint	20s
Build sources (ubuntu-22.04, i686-unknown-linux-gnu, true)	2m 35s
Test (ubuntu-22.04, x86_64-unknown-linux-gnu)	1m 9s
Build sources (ubuntu-22.04, aarch64-unknown-linux-gnu, true)	2m 33s
Test (ubuntu-22.04, x86_64-unknown-linux-musl)	1m 14s
Build sources (ubuntu-22.04, aarch64-unknown-linux-musl, true)	2m 34s
Test (windows-2022, x86_64-pc-windows-msvc)	1m 13s
Build sources (ubuntu-22.04, arm-unknown-linux-gnueabi, true)	2m 31s
Test (macos-12, x86_64-apple-darwin)	1m 31s
Build sources (ubuntu-22.04, arm-unknown-linux-musleabi, true)	2m 33s
Build sources (ubuntu-22.04, arm-linux-androideabi, true)	2m 37s
Build sources (ubuntu-22.04, arm-unknown-linux-gnueabihf, true)	2m 29s
Build sources (macos-12, aarch64-apple-darwin, false)	2m 30s
	25m 49s

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