Add dreaft of BPMN for cosmmoclmgrid

[gplssm]

fix #333

[gplssm]

cosmoclmgrid must be created before supply data is imported and preprocessed. The script ego_dp_supply_add_coastdat_gid.sql updates power plant tables with location information from cosmoclmgrid.
Therefore, in the structure BPMN, cosmoclmgrid needs to be linked to supply preprocessing in #336.
In #335 don't forget to document ego_dp_supply_add_coastdat_gid.sql.

[gplssm]

@IlkaCu, I completed the documentation here. I did

• Adding the script ego_dp_supply_add_coastdat_gid.sql
• Made sure that cosmoclm part is linked to supply part in the overview graphic

Could you please review?

I assign myself which means for me that I'm responsible for merging, once the review is done.

[IlkaCu]

It seems that script ego_dp_supply_add_coastdat_gid.sql is redundant and no integral part of the preprocessing.

1. it accesses the outdated table coastdat.cosmoclmgrid
2. column coastdat_gid is not (anymore) present in supply tables (e.g. model_draft.ego_dp_supply_res_powerplant), but replaced by w_id
3. w_id is assigned to supply tables in the dataprocessing itself in ego_dp_powerflow_assignment_otgid.sql accessing table coastdat.cosmoclmgrid
4. Table model_draft.ego_conv_powerplant_costdat_gid is not accessed in the dataprocessing or other preprocessing parts

Therefore I suggest to remove this script and adjust the BPMN accordingly.