Add support structure macro and modify v24c geometery accordingly

A separate macro has been introduced to generate the support structure using ROOT primitive solids. Version v24c (position at 410cm from COM) is functionally identical to v20b (positioned at 410cm) and v20c (positioned at z=370cm) with the addition of the support structure.For further details, please refer to the presentation from the TRD weekly group meeting: https://indico.gsi.de/event/22132/