Bring out model creation based on target to util

# Feature
## Desired Behavior / Functionality
Both the qmia and loss_traj are relying on classifiers. To make these agnostic to the input, we could use the target model as a blueprint.

## What Needs to Be Done
Bring out this functionality from qmia to utils and incorporate it into loss_traj

## How Can It Be Tested
Attacks should run