Fix Vite's native config compatibility diagnostics when bundling an `.mts` config. In a project whose package is CommonJS, Rolldown's internal virtual JavaScript modules can currently be mistaken for CommonJS files and trigger a false `esm-syntax-in-cjs` warning. Virtual module IDs are not project filesystem modules and must not be included in this compatibility check or classified based on the current working directory. Loading an otherwise compatible `.mts` config must emit no native-config compatibility warning, while diagnostics for real incompatible config files and imports must continue to work.