Allow folder tags to be overriden using the dbOverrides argument

LATOME firmware version v6 (HLS) is currently under testing. Processing data to ensure that there are no simulation mis matches with L1Calo can be done with this monitoring script but changes to the LAr readout mean that a special db tag must be used.

Adding support to --dbOverrides for overriding a tag

Tagging @will @hcai @admilic for information