Include ByteStream decoder for gFEX input

With this MR, the tool to decode the gFEX input is implemented. The input read out from the gFEX system needs to be combined into gTower information. The same routine used in the gFEX firmware to map fiber input to gTowers has been used here. Once the gTowers are defined, the corresponding information is used to fill the gTower EDM. Note that no trailer information has been saved yet.