pkill: implement `--queue` #1844

Job	Run time
cargo test (windows-latest)	2m 41s
Code Coverage (ubuntu-latest, unix)	2m 18s
cargo check (ubuntu-latest)	39s
cargo check (macOS-latest)	26s
cargo test (ubuntu-latest)	59s
Code Coverage (windows-latest, windows)	4m 57s
cargo test (macOS-latest)	44s
Code Coverage (macos-latest, macos)	2m 33s
Test each util separately (windows-latest)	3m 30s
Test each util separately (macOS-latest)	48s
Test each util separately (ubuntu-latest)	1m 4s
cargo check (windows-latest)	2m 37s
	23m 16s

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