cubicweb #2709703 add subcommands for cubicweb-ctl list [done]

in order to display only availables cubes, instances or configurations (eg. cubicweb-ctl list cubes).

prioritynormal
typeenhancement
done in<not specified>
load0.250
load left0.000
closed by#bb14dc9848ec [c-c list] add an optional argument to the list command (closes #2709703)
patch[c-c list] add an optional argument to the list command (closes #2709703) [applied]