Propose new backend interface DEP

[tanmayv25]

Proposing Backend Interface for addressing multiple non-functional requirements:

1. Standardized File structure.
2. Standardize Logging.
3. More maintainable code pieces.
4. Easier to add new features and add unit testing for them.
5. A lot of new features wouldn't require actual inference framework/GPU to be available.
6. Backend and Handler can be tested in isolation as well.
7. Easier to ensure consistent behavior across different backends.