Add commit-queue PR helpers (create/open) for jj bookmark heads #9

Job	Run time
build (aarch64-unknown-linux-gnu, ubuntu-latest)	4m 10s
build (x86_64-apple-darwin, macos-latest)	3m 1s
build (x86_64-unknown-linux-gnu, ubuntu-latest)	3m 6s
build (aarch64-apple-darwin, macos-latest)	4m 53s
release	8s
	15m 18s

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