Algorithm for LAr ByteStream reading

For @damazio and @pavol attention: A possible implementation of Re-entrant algorithm reading LArRawChannels for ByteStream.

Notes/Comments:

• So far reading the entire RawEvent and using the eformat::helper::create_toc to filter out LAr-fragments. Do we have somewhere a list of all LAr ROB-ids?
• I did not implement all the checks for data corruption we have in the old converter
• In this simple version, the cxx is less than 150 lines long with only ~30 lines of boilerplate code that could be shared with conversion-algorithms of LAr(Calib)Digits or LArFEBHeader.

Comments are welcome!