Update codes for reading FSR

Update PyConf config file including a function to read the Hlt decoding keys from the File Summary Record (FSR) persisted into input files.

Related integration test: LHCbIntegrationTests!73 (merged).

To be merged with DaVinci!1108 (merged) and LHCbIntegrationTests!73 (merged) and ref update DaVinci!1155 (merged)