ATLASRECTS-7574: adding CA for DESDM_ALLCELLS
This MR adds a component accumulator configuration for DESDM_ALLCELLS. For the time being, only egamma related quantities are stored in addition to the CaloCells. Potential users might bring feedback later if other quantities are needed.
This should solve the issue raised here : https://its.cern.ch/jira/browse/ATLASRECTS-7574