Use a unique identifier to identify seed hit module

identiferHash can be reused between pixel and strip detectors. If a pixel and strip element are included in the road and a seed hit falls on one of these shared hashes and the wrong type element occurs first in the road then the dynamic_cast of the prep raw data will become null leading to a segfault. Replace the identifierHash with Identifier so that the confusion is eliminated. Only relevant for seeds clusters, so not a significant increase in memory footprint as there are relatively few seeds per call.

JIRA: ATR-30292