* Make `Module::new` perform validation.
As noticed in #602, `Module::new` did not perform validation, which
turns out to be error-prone in practice. Rename it to
`Module::new_unchecked`, and add a new `Module::new` which does
perform validation.
Preserve wasm-c-api's `wasm_module_new`'s behavior by using
`Module::new_unchecked`, and implement `wasm_module_validate`.
* Change `validate`'s store argument to `&HostRef<Store>`.
* Enable multi-value in validation.
16b8b3e58d