[service-api] Add unified service API on `_cw` attribute This will allow writting generic entity code that could run on both client and repo side. This addition have been discussed with Sylvain Sylvain Thenault.

addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile