[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.
CSS Coding Standards--------------------(Draft, to be continued):Naming: camelCaseIndentation rules~~~~~~~~~~~~~~~~~- 2 espaces avant les propriétés- pas d'espace avant les ":", un espace après- 1 seul espace entre les différentes valeurs pour une même propriétéDocumentation~~~~~~~~~~~~~Please keep rules semantically linked grouped together, with a comment aboutwhat they are for.Recommendation~~~~~~~~~~~~~~- Try to use existing classes rather than introduce new ones- Keep things as simple as possible while in the framework- Think about later customization by application- Avoid introducing a new CSS file for a few lines of CSS, at least while the framework doesn't include packing functionalities