layers: Rework Destroy/Free data structure cleanup

layers: Rework Destroy/Free data structure cleanup

When destroying dispatchable objects we must cleanup internal data
structures prior to calling down the chain in the event that another
thread were to prempt execution and re-allocate a freed handle prior
to the layer cleanup code executing.

For non-dispatchable handles this shouldn't be a requirement due to
the fact that layers only see unique handles. However, moved some
non-dispatchable cleanup before the call to ICD as well for consistency
and to be extra safe.