Description of the change

Changes the config_schema Wasm API to match component semantics. This involves changing the name to config-schema and using a return area instead of WASI. Since config_schema is only called when using the default Javy plugin, this change shouldn't result in any functional changes.

Why am I making this change?

Reducing the scope of any PR to implement #962. This shouldn't break anything so seems harmless to get out of the way now.

Checklist

• I've updated the relevant CHANGELOG files if necessary. Changes to javy-cli and javy-plugin do not require updating CHANGELOG files.
• I've updated the relevant crate versions if necessary. Versioning policy for library crates
• I've updated documentation including crate documentation if necessary.