PrStoreUTHit - Adapt to UTDet changes, warn when a null sector ptr is received

Adapts to LHCb!2052 (merged) and adds warning

PrStoreUTHit  WARNING { UTChannelID : 0 : type=0 strip=0 sector=0 detRegion=0 layer=0 station=0 } gave NULL UT sector

which a UT expert should look into. It appears the vector returned by

for ( auto& sector : aBoard->sectorIDs() ) {
// ...
}

includes these invalid (null) IDs. This seems wrong, but an expert needs to take a look.

@cattanem I've added the same labels as LHCb!2052 (merged), hope this is OK.