Function register_cached_module 

pub fn register_cached_module(
    store: &mut Store,
    module_id: &str,
    cached: ModuleInterface,
    project_root: &Path,
)

Register a cached module in the store. display_path for each cached file is recomputed from the project layout against the current cwd, so warm and cold builds render the same diagnostic paths even though the cache stores only bare names.