Support differente parallelization options across structures

[t-reents]

Maybe add a general decorator/wrapper that could be used to parallellize inpainting and relaxation over structures.

It should support

• MPI parallelization. Either many CPU tasks or multiple GPUs (in this case, remember to set the torch device)
• Split the structures into multiple jobs (useful in case it's easier to submit several short jobs instead of one long running one)

Check the following parts of the WorkGraph to address point 2:

• https://aiida-workgraph.readthedocs.io/en/latest/concept/autogen/graph_task_concept.html
• https://aiida-workgraph.readthedocs.io/en/latest/howto/autogen/control_task_execution_order.html#grouping-dependencies-with-zone