Suggest check_concurrency when status reports an incorrect quantity

[facundofarias]

Problem

procodile status tells you when a process type is below its configured quantity:

 * worker only has 23 instances (should have 25)

but not what to do about it. The remedy is procodile check_concurrency, which is easy to miss — procodile start worker looks like the obvious candidate, but it is a no-op here, because Supervisor#start_processes skips any type that already has running instances:

next if @processes[process] && !@processes[process].empty?  # Process type already running

We hit this on a production host that had been sitting at 23/25 workers for weeks. The warning was visible in status the whole time; nobody acted on it because it didn't say what would fix it, and the command people reached for did nothing.

Change

Print a follow-up line naming the command whenever an incorrect_quantity message is present:

 * worker only has 23 instances (should have 25)
   Run `procodile check_concurrency` to start the missing process(es).

Notes

Added to StatusCLIOutput rather than Message.parse deliberately — Message.parse also backs procodile status --simple, whose one-line output is typically consumed by monitoring and should stay terse. --simple is unchanged.

Specs added in spec/specs/status_cli_output_spec.rb covering the quantity case, the non-quantity case, no messages, and mixed messages. Full suite green (39 examples).