TrigCompositeUtils: Optimize AlgToChain Tool

Optimize hotspots detected by v-tune in the AlgToChain Tool, to speed up the CostAnalysis script:

• Fix finding the right container based on the sequence/filter name
• Cache the event store keys per event. The caching is optional - done by calling cacheSGKeys function. Then the retrieveActiveChains, based on if the cached result is available or not, will call the retrieveActiveChainsForKeys function with cached or read keys and perform the chains retrieval. Caching is used for the TrigCostAnalysis client and will not be used for TrigErrorMon (called rarely, hopefully, so the per event caching is not needed)
• Use set and chain names instead of vector and TrigConf object (ensures a unique set of active chains associated with an algorithm)
• Use the boost function to find the right key for the sequence
• Reduce usage of StoreGate HLTMenu, instead use cached maps

Tagging @tamartin