Feature request: Have the rspec-queue executable output the queue size

Since ci-queue cannot by necessity respect before(:all) hooks, I have a workaround to run the required setup in my CI script. However, I'd like to avoid running it if the queue is empty (i.e. other workers have already exhausted it), so it would be cool to have something like:

unless `rspec-queue --query queue-size`.chomp! == '0'
  # do expensive setup
end

If there's already a straightforward programmatic way to do this, I'm happy to use that instead of adding a feature!

Start by locating the rspec-queue executable and reviewing how ci-queue exposes queue state. Check whether an existing programmatic query already reports the queue size; otherwise, done means supporting --query queue-size so it outputs the current size for CI scripts, including an empty queue as 0.