Moving to `BundleWorkflows` from MONAI

[surajpaib]

🚀 Feature Request

Reorganize Lighter internally to interface with BundleWorkflows. This way, Lighter can be run with the monai bundle interfaces as well.

Related Issue

https://github.com/project-lighter/lighter/issues/3

🔈 Motivation

This will support integration with the MONAI ecosystem

This is probably the best reference so far: https://github.com/Project-MONAI/tutorials/tree/main/bundle/python_bundle_workflow