pkill: implement `--queue` #1765

Job	Run time
cargo test (ubuntu-latest)	53s
cargo test (windows-latest)	41s
cargo check (ubuntu-latest)	49s
cargo test (macOS-latest)	37s
Code Coverage (macos-latest, macos)	49s
Test each util separately (macOS-latest)	1m 8s
Code Coverage (ubuntu-latest, unix)	1m 5s
Code Coverage (windows-latest, windows)	54s
Test each util separately (ubuntu-latest)	1m 19s
cargo check (windows-latest)	1m 49s
Test each util separately (windows-latest)	3m 23s
cargo check (macOS-latest)	26s
	13m 53s

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