cubicweb #856242 [selectors] have an hook selector over a full relation [rejected]

the current match_rtype is not sufficient as we sometimes see:

if self._cw.describe(self.eidfrom)[0] != 'SomeEtype':
    return

at the top of the Hook.call() method

a selector like:

match_spec('SomeEtype', 'an_rtype', '*')

could be nice, even more if it accepted etype unions like in:

match_spec(('SomeEtype', 'OtherEtype'), 'an_rtype', '*')
prioritynormal
typeenhancement
done in3.8.0
load0.000
load left0.000
closed by<not specified>