Migrate to Full MVVM Architecture

[Gold872]

Since the initial release of Elastic, the internal architecture has been getting shifted towards MVVM (Model, View, View Model). Currently, everything but the draggable container logic and preview building works off of this, however there are some parts of the app that aren't conventional with MVVM. For instance, the draggable container models have methods to build widgets out of them.

https://docs.flutter.dev/app-architecture/case-study