Add tofBin to stripDigiSimLink, associate recHit via simHit index

This PR consolidates previous PRs 4520 and 4661.  StripDigiSimLinks are modified to include the tofBin; strip digitizer builds simLinks with this additional information; TrackerHitAssociator uses direct simHit pointers for the strips.  The performance blow-up observed with PR 4520 is fixed, and redundancy in the simHit maps is removed.