[shell] provide autocompletion for rql queries in cubicweb-ctl shell (closes #3560541) Use the ``rql.suggestions`` component to complete user's input - readline calls the ``complete`` method with user's input, - the ``complete`` method asks for each known completers if it can suggest completions for user's input.

"""cubicweb-%(cubename)s application package

%(longdesc)s
"""