Preparation, Characterization, and Some Properties of a T-Cage-Type S-Bridged RhIII4ZnII3 Heptanuclear Complex with a Defective [Zn3HO]5+ Core. Crystal Structure of Spontaneously Resolved [{Rh(aet)3}4Zn3HO]Br5 (aet = 2-Aminoethanethiolate)