cubicweb-vcsfile #2897197 Add a notification machinery to make it possible to push mercurial repo updates instead of polling [validation pending]

prioritynormal
typeenhancement
done in1.13.0
load1.000
load left0.000
closed by#6e575e4b5531 [hooks] add a ZMQ subscriber to have push notif from hg repos (closes #2897197)
patch[hooks] add a ZMQ subscriber to have push notif from hg repos (closes #2897197) [applied]