cubicweb-celery #17081334 compat with CubicWeb 3.25 [validation pending]

compat with CubicWeb 3.25

Session is dropped in 3.25. AFAIK there is no backward compatible method to open a new connexion with another user, so let's add some compatibility code for 3.25 and early versions.

prioritynormal
typebug
done in0.3.1
load left0.000
closed by#8c75fdbcdeb1 compat with CubicWeb 3.25
patchcompat with CubicWeb 3.25 [applied]