Revert "Remove the need for HostRef<Module> (#778)"

This reverts commit 7b33f1c619.

Pushed a few extra commits by accident, so reverting this.

crates/misc/py/src/module.rs

@@ -4,5 +4,5 @@ use pyo3::prelude::*;
 
 #[pyclass]
 pub struct Module {
-    pub module: wasmtime::Module,
+    pub module: wasmtime::HostRef<wasmtime::Module>,
 }