[hook] remove assumption about entity cache vs cw_edited
We were assuming that if an entity is in the connection's cache, it has
a cw_edited attribute. This doesn't seem to always be the case. At
least in cubicweb 3.21, merging the web and repo-side caches makes this
more likely, but Denis says he's also seen this on 3.20.
addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile