Configure best-effort import behaviour for access control items

When importing principals and access control entries in the same package there are some scenarios that don't work out-of-the-box with FileVault content packages

• users and resource-based ACEs in the same content package; users are not guaranteed to be processed before ACEs ( see oak-dev@jacrabbit.apache.org: Installing users and access control entries in the same package )
• users and principal-based ACEs in the same content package ( see JCRVLT-472 )

A reasonable workaround for this kind of scenarios is to configure AuthorizationConfigurationImpl to have a "besteffort" import behaviour.