[python] resources are not embedded

>Haxe provides a simple resource embedding system that can be used for embedding files directly into the compiled application.

The [docs on resources](https://haxe.org/manual/cr-resources.html) suggest that they are always embedded, even if concrete implementation details vary a bit (several targets, including Python, are actually missing here btw). But the end result is always that you only have a single file to worry about.

On Python, something like this instead causes the resource to simply be _copied_ to a `main.py.test` file next to the `.py`:

```hxml
-python main.py
-resource test.txt@test
```

Is there a good reason for this? Wouldn't it make more sense to follow the same approach as the JS and Lua targets, where resources are embedded via static fields?

Sidenote: on PHP, resources don't seem to be embedded either, but that seems less problematic since that's already not generated as a self-contained file anyway.