Allow extracting arbitrary files to Mods/Cache

### I am planning on implementing this myself

Yes

### Describe your request

I'm currently developing a helper for Everest Core that's a wrapper on DearImGui, and I have everything working apart from automatically loading native libs.

Manually dumping the native libs into `Mods/Cache` allows Everest to load them just fine, but there's no way for my helper to put them there short of manually extracting them from the mod zip at mod initialisation.

I believe a cleaner way to do this would be to allow mod authors to explicitly list off additional files in the zip that should be extracted to `Mods/Cache`. I think it makes sense for this to go directly into everest.yaml.

```yaml
- Name: YourModName
Version: ...
DLL: ...
Resources:
- imgui.dylib
- imgui.so
- ...
Dependencies:
- Name: Everest
Version: 1.0.0
OptionalDependencies:
- Name: ...
Version: ...
```

### Additional context

_No response_