Add support for loading carts from .zip files
The main usecase would be to support multi-cart pico8 games on handheld devices that don't handle folders well/seamlessly. 

The expected format would be something like
```
"Readable Name.p8.zip":
 - codename-2.p8.png
 - codename-2-abc.p8.png
```
AND/OR
```
"Readable Name.p8.zip":
 - codename-2.p8
 - codename-2-abc.p8
```

Similar support is added in other emulators, e.g.
https://github.com/schellingb/dosbox-pure?tab=readme-ov-file#load-games-from-zip