[repo] move repo stats to Service (closes #2951067)
We currently add a new method on repo that anyone can call. Call service allows
to reach the same result with:
* Restricted access to manager only (thanks to selection on services),
* Less unrelated code on the repo.
* No need to fetch a reference to a repo object from client side.
`req._cnx.repo` is not an API and config.repository() is on its way out.
The old way to access this information (repo.stats()) is deprecated.
from cubicweb.schemas.base import in_group, CWSourceSchemaConfig
# copy __permissions__ to avoid modifying a shared dictionary
in_group.__permissions__ = in_group.__permissions__.copy()
in_group.__permissions__['read'] = ('managers',)
cw_for_source = CWSourceSchemaConfig.get_relation('cw_for_source')
cw_for_source.__permissions__ = {'read': ('managers', 'users'),
'add': ('managers',),
'delete': ('managers',)}