Turn PSM into a complete blackbox

Turn PSM into a complete blackbox
- The psm structures aren't stored or passed around by any users,
  so there's no need for them to separately allocate and free the
  struct, bury this all inside rpmpsmRun() which takes care of
  initialization, actual actions and freeing.
- There's also no need for refcounting now as allocations are completely
  contained within the rpmpsmRun() blackbox. Lose psm-debug foo which
  was only used for refcount debugging.
- No functional changes