Allow same directory entry id in different tenants

When a directory is set up to be used in a multitenant isolation, it is not possible to add a new entry if the id is the same as an id not associated to any tenant. The reason is that the computation of the id with the tenant id is done after checking if the id exists.
Also, it could lead to an issue because the check if the id exists is done before the computation so it is possible that the computed id is the same as an existing id in the directory.