pkill: implement `--queue` #1766

Job	Run time
cargo check (macOS-latest)	26s
cargo check (windows-latest)	1m 55s
cargo test (windows-latest)	2m 26s
cargo test (macOS-latest)	39s
Test each util separately (macOS-latest)	44s
cargo test (ubuntu-latest)	1m 4s
cargo check (ubuntu-latest)	46s
Test each util separately (ubuntu-latest)	1m 14s
Test each util separately (windows-latest)	3m 24s
Code Coverage (macos-latest, macos)	1m 55s
Code Coverage (ubuntu-latest, unix)	2m 23s
Code Coverage (windows-latest, windows)	4m 41s
	21m 37s

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