make benchm yaml work

[lisab00]

part of solving #403

I included "Shared params" in all yaml files. Did have no time to test whether they are working, though.
following files I did not amend, but tested functionality:

• "benchmark_mnist_shared_hyper_grid.yaml" is working
• "benchmark_pacs_resnet.yaml" not working (looks like error in diva, rest seems to work)
• "benchmark_pacs_resnet_on_mnist.yaml" is working
• "color_mnist_erm_vs_diva.yaml" not working cause no shared params (Carla hopefully fixed this bug, see bugfix if shared params does not exist in yaml #478)