Add `multivalue` target feature to WASM target
This PR is similar to #99643 and #97808. It addresses #96472 for the `multivalue` target feature.
The problem I am trying to fix is to remove the following warning when compiling with `-C target-feature=+multivalue` for `--target=wasm32-unknown-unknown`.
```
warning: unknown feature specified for `-Ctarget-feature`: `multivalue`
|
= note: it is still passed through to the codegen backend
= note: consider filing a feature request
```