Minor changes for components related to wit-bindgen support (#5053)

* Plumb type exports in components around more

This commit adds some more plumbing for type exports to ensure that they
show up in the final compiled representation of a component. For now
they continued to be ignored for all purposes in the embedding API
itself but I found this useful to explore in `wit-bindgen` based tooling
which is leveraging the component parsing in Wasmtime.

* Add a field to `ModuleTranslation` to store the original wasm

This commit adds a field to be able to refer back to the original wasm
binary for a `ModuleTranslation`. This field is used in the upcoming
support for host generation in `wit-component` to "decompile" a
component into core wasm modules to get instantiated. This is used to
extract a core wasm module from the original component.

* FIx a build warning

crates/wasmtime/src/component/instance.rs

@@ -578,7 +578,7 @@ impl<'a, 'store> ExportInstance<'a, 'store> {
                 func,
                 options,
             )),
-            Export::Module(_) | Export::Instance(_) => None,
+            Export::Module(_) | Export::Instance(_) | Export::Type(_) => None,
         }
     }