Goto dependency definition

Haskell Language Server (HLS) currently supports Goto Definition only for symbols defined within a user’s project, making it difficult to inspect implementations of functions imported from external dependencies. This project extends that functionality to third-party libraries by enabling developers to navigate directly to dependency source code from within their IDE. The solution leverages .hie files generated by GHC and indexed via HieDb. During HLS startup, dependency HIE files will be discovered and indexed, allowing symbol lookups to resolve to external modules. When a user triggers goto definition on a dependency symbol, the corresponding source code will be extracted from the HIE file, written to a deterministic location, and opened in the editor. To ensure correctness, a type-level rule system will be introduced to prevent invalid rule execution on dependency files, replacing the current fragile runtime whitelist approach. The project deliverables include: rebasing and stabilizing the existing prototype (PR #3749), implementing a type-safe rule constraint system, ensuring complete rule coverage across file types, improving user experience through automated HIE file generation and indexing, enforcing read-only handling for dependency files, and exploring solutions for supporting boot libraries via prebuilt HIE artifacts. These improvements aim to deliver a robust, maintainable, and seamless dependency navigation experience in HLS.