Improve logging with Tracker

[vijusudhi]

Currently, the platform only supports W&B tracker. Extend this and improve the logging.

TODOs:

• Create an interface for the tracker.
• Separate frontend and backend concerns in the tracker.
  For example: now, the tracker has support for generating plotly figures. This should be separated from the backend code.
• Add capabilities to log custom metrics both with the Train and Eval loggers.