Cleans up the WASM environment handling.

Instead of passing the entire script resolver as a pointer to the WebAssemblyEnv, we now have split off the data actually relevant to the environment into it's own class, which is stored inside of an Arc.

src/static_data/species_data/species.rs

@@ -28,6 +28,7 @@ pub struct Species {
 /// A cached String Key to get the default form.
 static DEFAULT_KEY: conquer_once::OnceCell<StringKey> = conquer_once::OnceCell::uninit();
 
+/// Gets the StringKey for "default". Initialises it if it does not exist.
 fn get_default_key() -> StringKey {
     DEFAULT_KEY.get_or_init(|| StringKey::new("default")).clone()
 }