cubicweb-jsonschema #17086899 get rid of /<etype>/relationships/<rtype> routes/views [validation pending]

Find a way to implement the same feature using existing routing. In particular, this route currently support "reverse" relation. We should handle this explicitly (like with a <rtype>-object URL segment) I think.

priorityimportant
typetask
done in0.3.0
load2.000
load left0.000
closed by#72d14b3b538e Remove /<etype>/relationships/<rtype> views and respective resource