Prevent from having duplicated entries in ACLS table

Some users reported that their ACLS tabl contains duplicated entries after a while, which could produce too long ACLS and make the READ ACLS cache fail to be

(Currently we don't have a reproduction case.)

A check should be added in org.nuxeo.ecm.core.api.security.ACL#setACEs to emit a WARN when there are duplicate ACPs.
–
There is now a WARN log when ACL.setACEs contains duplicate entries.

WARN  [ACLImpl] Setting an ACL with at least one duplicate entry: ACE(...) , ACL entries: ...

By setting the log4j level to TRACE there is a stack trace available.

  <logger name="org.nuxeo.ecm.core.api.security.impl">
    <level value="TRACE" />
  </logger>