CA-based script to populate the LAr Bad Feb database

I just noticed that this rarely-used script was never migrated to CA. Done now.

Works also for the known-mini-noise-burst-febs with a syntax like:

LArBuildMissingFebDB.sh -append 470100 0 newFebs.txt /LAR/BadChannelsOfl/KnownMNBFEBs

cc @pavol, @ekay