Fix IOpaqueAddress lifetime in EvtStoreSvc

Extend the IOpaqueAddress lifetime in setRoot and registerAddress to be the same as the object created from the address by pushing it into the same Entry.

This fixes a problem with reifying the LHCb RawEvent in case the RawDataCnvSvc is used without the 'copy' option. In that scenario, the data itself is owned by the IOpaqueAddress and the RawEvent is just a 'view', and letting the IOpaqueAddress go out of scope will result in the data being overwritten with 'interesting' consequences...