Implement training and testing loop

[JankowskiDaniel]

Implement the main training loop according to the template:

def train_model():
      for e in range(epochs):
            train_epoch()

Moreover, implement the script for testing the model.

Both scripts should save intermediate and final results into the specified directory.

[kapiblue]

Testing script implemented 47abf8e42f0df81c532edc976909e09d6a34ff8d

[kapiblue]

Calculating metrics using torchmetrics and saving to csv implemented: cd98eb2a515eeb9a7a4f2af3414128a92355ece6

[kapiblue]

For now, both scripts are done.

We need to be careful with shuffling the datasets and dataloaders.