TrigCost: Add algorithm to chain mapping

Add algorithm name to chain object mapping as a part of chain cost monitoring.

AlgToChain algorithm:

• store TrigConf::Chain instead of just names
• add function to return map with chains for all available algorithms
• add function to return chain objects for given algorithm name

TrigCost:

• add AlgToChain to TrigCostAnalysis
• store alg to chains map in CostData

Follow up:

• use the navigation to remove chains from the list which didn't run in any Step which executed Alg
• process chains and create histograms to ntuple
• postprocessing for chains - create csv tables to display on Trig Cost Browser

Tagging @tamartin @mark