[entity] Add a cw_related_rqlst method returning the RQL select node of cw_related method
This is useful if one wants to modify the query before execution.
A bit a PEP8 style fix in tests along the way.
Related to #12306543.
Web side development
====================
In this chapter, we will describe the core APIs for web development in
the *CubicWeb* framework.
.. toctree::
:maxdepth: 2
publisher
controllers
request
searchbar
views/index
rtags
ajax
js
css
edition/index
facets
internationalization
property
httpcaching
resource