Add header files used for encoding and decoding Allen LumiSummary banks
Adds the headers common to encoding and decoding the Allen LumiSummary banks. The decoding is added by !3518 (merged) and the encoding by Allen!743 (merged) and Allen!950 (merged). As !3518 (merged) has additional dependencies (Rec!3108 (merged) and Moore!1761 (merged), which additionally depend on some Panoramix changes), these two headers have been separated out into their own MR to allow Allen!950 (merged) to be merged.