Make wasmtime_environ::Module serializable (#2005)

* Define WasmType/WasmFuncType in the Cranelift
* Make `Module` serializable

cranelift/codegen/src/ir/valueloc.rs

@@ -98,6 +98,7 @@ impl<'a> fmt::Display for DisplayValueLoc<'a> {
 /// - For register arguments, there is usually no difference, but if we ever add support for a
 ///   register-window ISA like SPARC, register arguments would also need to be translated.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub enum ArgumentLoc {
     /// This argument has not been assigned to a location yet.
     Unassigned,