cubicweb #3181499 [req] deprecate CWCache machinery [validation pending]

Move it to a cube.

prioritynormal
typeenhancement
done in3.19.0
load0.500
load left0.000
closed by#fbf2287fb2ce [req] deprecate get_cache (closes #3181499)
patch[req] deprecate get_cache (closes #3181499) [applied]