better support for custom scalars and enums

[lolopinto]

we currently throw if a custom scalar or enum is referenced directly

https://github.com/lolopinto/ent/blob/90db3c9984b4ab14a6342d720464fc18a081b164/ts/src/graphql/graphql.ts#L564-L575

possible that we can be smart and use the imports that we take to map to the type?