streamline HltPackedBuffer{Decoder,Writer}
A few tiny optimizations to HltPackedBuffer{Writer,Decoder}:
- avoid unnecessary vector of strings
- factor mapping of locationID -> output index in separate function
- factor debug printout of header into separate function
- prefer LHCb::Algorithm over Gaudi::Functional and drop use of Error in favor of MsgCounter
and remove HltPackedData{Writer,Decoder}