Update lumi en/de-coders and monitor for HLT2 lumi counters

Various changes to LHCb needed to add the Hlt2 luminosity line. Specifically:

• HltLumiWriter and HltLumiSummaryDecoder now use SourceIDs
  • as the previous functionality of HltLumiSummaryDecoder (to combine all banks present into a single HltLumiSummary object regardless of SourceID) is potentially also useful, this is retained if sourceID==SourceID::Dummy
• The machinery related to SourceIDs has been updated to support LumiSummary banks
• PyConf.application.configure now flushes all key_registries to git rather than just the ANN registry

Test with Moore!2454 (merged), Rec!3472 (merged) and MooreOnline!248 (merged)