Add a CLI option to only create/refresh/delete a single object

[maxbes]

A somewhat common use case is to force synchronization for a single user. For example, a LSC might run every night to synchronize the entire tree, but we urgently need to update one user.

There seems to be no easy way to do this at the moment

It would be nice to be able to be able to override the "getAllFilter" phase (and equivalent for DB) by providing the pivot ourselves

Example:

lsc -s all --only myuser