fix: corrected projection calculation of camera sub view (#15646)

# Objective

- Fixes #15600

## Solution

- The projection calculations did not use the aspect ratio of
`full_size`, this was amended

## Testing

- I created a test example on [this
fork](https://github.com/m-edlund/bevy/tree/bug/main/subViewProjectionBroken)
to allow testing with different aspect ratios and offsets
- The sub view is bound to a view port that can move across the screen.
The image in the moving sub view should "match" the full image exactly

## Showcase

Current version:


https://github.com/user-attachments/assets/17ad1213-d5ae-4181-89c1-81146edede7d

Fixed version:


https://github.com/user-attachments/assets/398e0927-e1dd-4880-897d-8157aa4398e6