Integrate the Chest Xray/Pneumonia dataset to client implementation

[tem556]

Fixed some bugs that caused problems with the healthdataset. The health dataset can now successfully run with a federated learning setting.

[gnahtb]

Instead of adding a boolean variable in the Cifar10Repository class, can you create a separate ChestXrayRepository class? This is the single responsibility principle in OOP, where each class holds only one responsibility. You might also read about the Factory pattern, which might be relevant.

[tem556]

I tired out a different structure that tries to follow the singe responsibility principle. Let me know what you think @bnnthang