[ticket/12602] Add command to print the cron list

Add command to print 2 lists of registered tasks :
The ready and the not ready ones.
This is not better. I was not talking about the language key name itself. I was talking about the language string value. "No cron task needs to be run right now." is just wrong. This command is for listing all existing cron tasks, regardsless of whether they are ready or not.