fed prox example

[mattiasakesson]

Description

[mattiasakesson]

Updated. I didnt add a notbok instead a wrote some lines in the readme about how to use fedprox and how to turn the example to vanilla fedavg by setting mu=0. I dont think a notebok will make it any clearer, you still have to manually modify the client_settings.yaml file to change the mu parameter.

[ahellander]

Will it / how will it work with client_settings.yaml in the base directory and not in the 'client' folder?

Also, we need to rework to align with the new model incoming from the "python_env" PR.

[ahellander]

Given the release with the python_env support, this one needs to be updated to the new client structure.