[frontendc] Implement schema resolving logic #2
Description
In schema_normalizer.rs we need to iterate through refs and expand them. First, we'd need to build a map of all components in the schema, and then map all refs to expanded objects. However, if we just replace all refs with objects, we wouldn't be able to support recursive types. So we probably just need to build an internal index of types and pass it to backendc in CompileRequest.