For this phase, the goal is to parse all the references in a file and using them to link together definition nodes in the graph. Notably, we only aim to handle _intra-file_ references –– i.e. references to constructs that are defined in the same file as the reference. This phase will involve updating the language parsers to capture references and compute their FQNs. Once that's done, the reference parser must be integrated into the indexer and used to resolve links between definition nodes, which will be loaded into Kuzu.