Add code for plots/update functions associated with `normalize`, `average`, `prepare`, and `benchmark`

[tacazares]

We currently only produce plots for train and benchmark. It would be nice to add some additional plotting functions.

• [ ] Plot bar plot of max values across chromosomes in normalize
• [ ] Fix the broken benchmark plot
• [ ] Beautify the train plot for loss and dice coefficient
• [ ] Plot the training ROI statistics?
• [ ] We could plot the Pearson correlation as heatmaps or scatterplots for the replicates going into average
• [ ] We could plot specific signal track regions in predict if an ROI is given
• [ ] We could add QC figures to prepare such as fragment length distribution and TSS enrichment
• [ ] Add code for visualizing ROI specific predictions using variants