Register VP daughters with updatemgrservice

The main VP detector element (DeVP) caches geometry data. Those data need to be updated with condition (alignment) changes. Although DeVP registers changes of its conditions with the updatemanagersvc, it doesn't do so for the daughters. As a result, alignment updates of the daughters do not trigger an update of the cache and the alignment does not work.

This merge requests addresses this problem by registering the callback in DeVP with all the IGeometryInfo objects of the daughters in the VP geometry tree. It is not clear why we need this, as it was not done in the past.

See also the discussion in https://its.cern.ch/jira/browse/LHCBPS-1850