gFEX mapping update in phi

With this MR the phi binning of the gTowers in the most forward region is updated in the simulation. Changes reflect the actual gTower binning used in the firmware. The changes required to modify the gTowerBuilder class, the supercells assignment in the gSuperCellTowerMapper class, as well as the gFEXSim, gFEXSysSim, gFEXFPGA tools where the gTowers are used. The new binning has been validated at every step of the simulation. Additionally, the use of constant values for indicating the number of eta and phi bins has been has been expanded to improve code readability.